std::fs: slightly reformat remove_dir_all error docs

To make the error cases easier to spot on a quick glance.

Author: jieyouxu

std/src/fs.rs

@@ -2841,9 +2841,11 @@ pub fn remove_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
 ///
 /// See [`fs::remove_file`] and [`fs::remove_dir`].
 ///
-/// `remove_dir_all` will fail if `remove_dir` or `remove_file` fail on any constituent paths, including the root `path`.
-/// As a result, the directory you are deleting must exist, meaning that this function is not idempotent.
-/// Additionally, `remove_dir_all` will also fail if the `path` is not a directory.
+/// [`remove_dir_all`] will fail if [`remove_dir`] or [`remove_file`] fail on *any* constituent
+/// paths, *including* the root `path`. Consequently,
+///
+/// - The directory you are deleting *must* exist, meaning that this function is *not idempotent*.
+/// - [`remove_dir_all`] will fail if the `path` is *not* a directory.
 ///
 /// Consider ignoring the error if validating the removal is not required for your use case.
 ///