Rollup merge of #117639 - rustbot:docs-update, r=ehuss

Update books

## rust-lang/reference

4 commits in 16fd3c06d9e558dae2d52000818274ae70c9e90a..cd8193e972f61b92117095fc73b67af767b4d6bc
2023-11-04 17:19:39 UTC to 2023-10-30 16:04:52 UTC

- Guarantee that raw pointer conversions preserve slice element count (rust-lang/reference#1417)
- some asm block flags also mean there can be no fences (rust-lang/reference#1413)
- Guarantee `char` layout (rust-lang/reference#1401)
- Doc: Add the RISC-V stabilized target features (rust-lang/reference#1415)

## rust-lang/rust-by-example

3 commits in 6709beeb7d0fbc5ffc91ac4893a24434123b9bfa..311b84962016b28c75525c86e7b3f49fd9101a39
2023-10-31 18:32:09 UTC to 2023-10-31 18:30:39 UTC

- Fixed explanation mistake in comment (rust-lang/rust-by-example#1761)
- Fix typos (rust-lang/rust-by-example#1759)
- docs(9.2): fix typo (rust-lang/rust-by-example#1754)

## rust-lang/rustc-dev-guide

6 commits in b0ee9ec8fa59a6c7620165e061f4747202377a62..77dbe5782b2488af3bb489ad702eaff438f465bf
2023-11-06 16:14:34 UTC to 2023-10-29 17:16:02 UTC

- add a new type system invariant (rust-lang/rustc-dev-guide#1822)
- Update some outdated descriptions of coverage instrumentation (rust-lang/rustc-dev-guide#1809)
- Add some documentation for unsizing (rust-lang/rustc-dev-guide#1817)
- Bibliography: fixing author of "You Can't Spell Trust Without Rust" (rust-lang/rustc-dev-guide#1815)
- remove change-id from sample build configuration (rust-lang/rustc-dev-guide#1813)
- Update name of "active" features to "unstable" (rust-lang/rustc-dev-guide#1814)