Replaces instances of -p with --root-prefix in documentation

[SylvainCorlay]

Fixes #3408

[jjerphan]

LGTM.

On main, those are the only occurrences of shell init with -p to be changed with -r, ditto for shell hook.

ag "shell init"

docs/source/developer_zone/changes-2.0.rst:35:- ``micromamba shell init`` root prefix parameter ``--prefix`` (``-p``) was renamed
docs/source/installation/micromamba-installation.rst:112:If you want to persist these changes, you can automatically write them to your ``.bashrc`` (or ``.zshrc``) by running ``./micromamba shell init ...``.
docs/source/installation/micromamba-installation.rst:118:  ./bin/micromamba shell init -s bash -p ~/micromamba  # this writes to your .bashrc file
docs/source/installation/micromamba-installation.rst:124:  ./micromamba shell init -s zsh -p ~/micromamba
docs/source/installation/micromamba-installation.rst:167:  .\micromamba.exe shell init -s powershell -p C:\Your\Root\Prefix
docs/source/user_guide/micromamba.rst:23:    shell                       Generate shell init scripts
libmamba/data/mamba.fish:133:  shell                       Generate shell init scripts
libmamba/src/api/configuration.cpp:728:                                << " shell init ...' to initialize your shell\n"
libmamba/src/api/configuration.cpp:729:                                   "    (then restart or source the contents of the shell init script)\n"
libmamba/src/core/shell_init.cpp:293:            "# !! Contents within this block are managed by '{mamba_exe_name} shell init' !!\n"
libmamba/src/core/shell_init.cpp:319:            "# !! Contents within this block are managed by '{mamba_exe_name} shell init' !!\n"
libmamba/src/core/shell_init.cpp:362:                << " shell init' !!\n";
libmamba/src/core/shell_init.cpp:396:                << " shell init' !!\n";
libmamba/src/core/shell_init.cpp:422:                << " shell init' !!\n";
libmamba/src/core/shell_init.cpp:493:                << " shell init' !!\n";
libmamba/src/core/shell_init.cpp:968:        out << "# !! Contents within this block are managed by 'mamba shell init' !!\n";
libmamba/CHANGELOG.md:215:- Remove micromamba shell init -p by @AntoinePrv in https://github.com/mamba-org/mamba/pull/3092
libmamba/CHANGELOG.md:1114:- Fix shell init with relative paths (@adriendelsalle) #1252
libmamba/CHANGELOG.md:1154:- Continue `shell init` when we can't create the prefix script dir (thanks @maresb)
libmamba/CHANGELOG.md:1257:- [micromamba] shell init will try attempt to enable long paths support on
libmamba/CHANGELOG.md:1334:- [micromamba] fix multiple shell init with cmd.exe (@adriendelsalle) #915
libmamba/CHANGELOG.md:1358:- [libmamba] make prefix mandatory for shell init (@adriendelsalle) #896
libmamba/CHANGELOG.md:1385:- [libmamba] remove confirmation prompt of root_prefix in shell init #874
libmambapy/CHANGELOG.md:654:- Continue `shell init` when we can't create the prefix script dir (thanks @maresb)
libmambapy/CHANGELOG.md:757:- [micromamba] shell init will try attempt to enable long paths support on
libmambapy/CHANGELOG.md:834:- [micromamba] fix multiple shell init with cmd.exe (@adriendelsalle) #915
libmambapy/CHANGELOG.md:858:- [libmamba] make prefix mandatory for shell init (@adriendelsalle) #896
libmambapy/CHANGELOG.md:885:- [libmamba] remove confirmation prompt of root_prefix in shell init #874
micromamba/src/shell.cpp:320:        // ``micromamba shell init --shell bash`` and ``micromamba shell --shell bash init`` were
micromamba/src/umamba.cpp:42:    CLI::App* shell_subcom = com->add_subcommand("shell", "Generate shell init scripts");
micromamba/src/activate.cpp:75:                "    $ {exe} shell init --shell {1} --root-prefix=~/.local/share/mamba\n"
micromamba/tests/test_activation.py:322:    s = [f"{umamba} shell init -r {rpv} {xonsh_shell_args(interpreter)}"]
micromamba/tests/test_activation.py:338:    s = [f"{umamba} shell init -r {rpv} {xonsh_shell_args(interpreter)}"]
micromamba/tests/test_activation.py:355:        s = [f"{umamba} shell init -r {rpv}"]
micromamba/tests/test_activation.py:376:        s = [f"{umamba} shell init -r {rpv}"]
micromamba/tests/test_activation.py:385:    s = [f"{umamba} shell init -r {other_root_prefix} {xonsh_shell_args(interpreter)}"]
micromamba/tests/test_activation.py:441:    s = [f"{umamba} shell init -r {tmp_root_prefix} {xonsh_shell_args(interpreter)}"]
micromamba/tests/test_activation.py:473:    s = [f"{umamba} shell init -r {tmp_root_prefix} {xonsh_shell_args(interpreter)}"]
micromamba/tests/test_activation.py:515:    s = [f"{umamba} shell init -r {tmp_root_prefix} {xonsh_shell_args(interpreter)}"]
micromamba/tests/test_activation.py:545:    s = [f"{umamba} shell init -r {tmp_root_prefix}"]
micromamba/tests/test_activation.py:644:    s = [f"{umamba} shell init -r {tmp_root_prefix}"]
micromamba/tests/test_activation.py:763:    s = [f"{umamba} shell init -r {tmp_root_prefix}"]
micromamba/tests/test_activation.py:919:        f"{format_path(mamba_exe, interpreter)} shell init -s {interpreter} -r {format_path(tmp_root_prefix, interpreter)}"
micromamba/CHANGELOG.md:156:- Remove micromamba shell init -p by @AntoinePrv in https://github.com/mamba-org/mamba/pull/3092
micromamba/CHANGELOG.md:447:- fix: let the new executable run the shell init script by @ruben-arts in https://github.com/mamba-org/mamba/pull/2529
micromamba/CHANGELOG.md:687:- Fix `shell init --dry-run` (thanks @jonashaag) #1767
micromamba/CHANGELOG.md:932:- Continue `shell init` when we can't create the prefix script dir (thanks @maresb)
micromamba/CHANGELOG.md:1035:- [micromamba] shell init will try attempt to enable long paths support on
micromamba/CHANGELOG.md:1112:- [micromamba] fix multiple shell init with cmd.exe (@adriendelsalle) #915
micromamba/CHANGELOG.md:1136:- [libmamba] make prefix mandatory for shell init (@adriendelsalle) #896
micromamba/CHANGELOG.md:1163:- [libmamba] remove confirmation prompt of root_prefix in shell init #874
CHANGELOG.md:256:- [libmamba, micromamba] Remove micromamba shell init -p by @AntoinePrv in https://github.com/mamba-org/mamba/pull/3092
CHANGELOG.md:670:- [micromamba] fix: let the new executable run the shell init script by @ruben-arts in https://github.com/mamba-org/mamba/pull/2529
CHANGELOG.md:1050:- [micromamba] Fix `shell init --dry-run` (thanks @jonashaag) #1767
CHANGELOG.md:1362:- [libmamba] Fix shell init with relative paths (@adriendelsalle) #1252
CHANGELOG.md:1406:- Continue `shell init` when we can't create the prefix script dir (thanks @maresb)
CHANGELOG.md:1509:- [micromamba] shell init will try attempt to enable long paths support on
CHANGELOG.md:1586:- [micromamba] fix multiple shell init with cmd.exe (@adriendelsalle) #915
CHANGELOG.md:1610:- [libmamba] make prefix mandatory for shell init (@adriendelsalle) #896
CHANGELOG.md:1637:- [libmamba] remove confirmation prompt of root_prefix in shell init #874

Ditto for shell hook:

ag shell hook

docs/source/installation/micromamba-installation.rst:108:  eval "$(./bin/micromamba shell hook -s posix)"
docs/source/installation/micromamba-installation.rst:110:This shell hook modifies your shell variables to include the micromamba command.
docs/source/installation/micromamba-installation.rst:164:  .\micromamba.exe shell hook -s powershell | Out-String | Invoke-Expression
libmamba/src/core/activation.cpp:249:        // normal conditions, if the shell hook is working correctly, this should
libmamba/CHANGELOG.md:202:- Update shell hook comments by @jonashaag in https://github.com/mamba-org/mamba/pull/3051
libmamba/CHANGELOG.md:515:- fix: added missing hook_preamble() for powershell hook by @chawyehsu in https://github.com/mamba-org/mamba/pull/2761
micromamba/src/activate.cpp:27:                "{} shell hook -s powershell | Out-String | Invoke-Expression",
micromamba/src/activate.cpp:31:        return fmt::format(R"sh(eval "$({} shell hook --shell {})")sh", executable_name, guessed_shell);
micromamba/tests/test_shell.py:87:                f.write(f"@Echo off\r\n{umamba} shell hook --json")
micromamba/tests/test_shell.py:92:                f.write(f"& {umamba} shell hook --json")
micromamba/tests/test_shell.py:96:                f.write(f"{umamba} shell hook --json")
micromamba/tests/test_shell.py:229:    subprocess.check_call(["dash", "-c", f"eval $({umamba} shell hook -s dash)"])
micromamba/tests/test_shell.py:230:    subprocess.check_call(["dash", "-c", f"eval $({umamba} shell hook -s posix)"])
micromamba/CHANGELOG.md:565:- Fix micromamba shell completion when running 'shell hook' directly by @TomiBelan in #2137
CHANGELOG.md:242:- [libmamba] Update shell hook comments by @jonashaag in https://github.com/mamba-org/mamba/pull/3051
CHANGELOG.md:514:- [libmamba] fix: added missing hook_preamble() for powershell hook by @chawyehsu in https://github.com/mamba-org/mamba/pull/2761
CHANGELOG.md:889:- [micromamba] Fix micromamba shell completion when running 'shell hook' directly by @TomiBelan in #2137
libmamba/src/core/shell_init.cpp:296:            R"sh(__mamba_setup="$("$MAMBA_EXE" shell hook --shell {shell} --root-prefix "$MAMBA_ROOT_PREFIX" 2> /dev/null)")sh"
libmamba/src/core/shell_init.cpp:324:            R"sh(eval "$("$MAMBA_EXE" shell hook --shell {shell} --root-prefix "$MAMBA_ROOT_PREFIX")")sh"
libmamba/src/core/shell_init.cpp:368:        content << "                   \'Autogenerated from $($MAMBA_EXE shell hook -s xonsh -r $MAMBA_ROOT_PREFIX)\')\n";
libmamba/src/core/shell_init.cpp:369:        content << "__xonsh__.execer.exec($($MAMBA_EXE shell hook -s xonsh -r $MAMBA_ROOT_PREFIX),\n";
libmamba/src/core/shell_init.cpp:371:        content << "                      filename=\'$($MAMBA_EXE shell hook -s xonsh -r $MAMBA_ROOT_PREFIX)\')\n";
libmamba/src/core/shell_init.cpp:399:        content << "$MAMBA_EXE shell hook --shell fish --root-prefix $MAMBA_ROOT_PREFIX | source\n";
libmamba/src/core/shell_init.cpp:427:        // TODO the following shouldn't live here but in a shell hook