Try to make it a little clearer that cargo package/publish will rebui…

…ld from scratch.

Closes #3062

src/doc/man/cargo-package.adoc

@@ -33,6 +33,9 @@ steps:
       about the current VCS checkout hash if available (not included with
       `--allow-dirty`).
 . Extract the `.crate` file and build it to verify it can build.
+    - This will rebuild your package from scratch to ensure that it can be
+      built from a pristine state. The `--no-verify` flag can be used to skip
+      this step.
 . Check that build scripts did not modify any source files.
 
 The list of files included can be controlled with the `include` and `exclude`

src/doc/man/generated/cargo-package.html

@@ -59,6 +59,15 @@ <h2 id="cargo_package_description">DESCRIPTION</h2>
 </li>
 <li>
 <p>Extract the <code>.crate</code> file and build it to verify it can build.</p>
+<div class="ulist">
+<ul>
+<li>
+<p>This will rebuild your package from scratch to ensure that it can be
+built from a pristine state. The <code>--no-verify</code> flag can be used to skip
+this step.</p>
+</li>
+</ul>
+</div>
 </li>
 <li>
 <p>Check that build scripts did not modify any source files.</p>

src/etc/man/cargo-package.1

@@ -2,12 +2,12 @@
 .\"     Title: cargo-package
 .\"    Author: [see the "AUTHOR(S)" section]
 .\" Generator: Asciidoctor 2.0.10
-.\"      Date: 2019-11-21
+.\"      Date: 2019-12-19
 .\"    Manual: \ \&
 .\"    Source: \ \&
 .\"  Language: English
 .\"
-.TH "CARGO\-PACKAGE" "1" "2019-11-21" "\ \&" "\ \&"
+.TH "CARGO\-PACKAGE" "1" "2019-12-19" "\ \&" "\ \&"
 .ie \n(.g .ds Aq \(aq
 .el       .ds Aq '
 .ss \n[.ss] 0
@@ -132,6 +132,19 @@ about the current VCS checkout hash if available (not included with
 .  IP " 3." 4.2
 .\}
 Extract the \fB.crate\fP file and build it to verify it can build.
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+This will rebuild your package from scratch to ensure that it can be
+built from a pristine state. The \fB\-\-no\-verify\fP flag can be used to skip
+this step.
+.RE
 .RE
 .sp
 .RS 4