Align no_std intro language better and reword

We had said here that the `no_std` attribute is used to "prevent the
automatic linking of the std crate", but then further down we say,
"using `no_std` does not prevent the standard library from being
linked in".

The important distinction here is the word "automatically", but that
gets a bit lost due to reusing the "prevent" phrasing.

Probably "prevent" is just too strong a word to use when what we're
really saying is that we're causing something to not happen
automatically.  Let's make that more clear and increase sentence
parallelism.

Author: traviscross

src/names/preludes.md

@@ -81,7 +81,7 @@ r[names.preludes.extern.no_std]
 ### The `no_std` attribute
 
 r[names.preludes.extern.no_std.intro]
-The *`no_std` [attribute][attributes]* is used to prevent the automatic linking of the [`std`] crate, deferring to [`core`] instead.
+The *`no_std` [attribute][attributes]* causes the [`std`] crate to not be linked automatically, deferring to the [`core`] crate instead.
 
 > [!EXAMPLE]
 > <!-- ignore: test infrastructure can't handle no_std -->