Standardize some final help strings. We're done, aside from typos. props zeo,...

Standardize some final help strings. We're done, aside from typos. props zeo, jane, duck_, fixes #19020.

git-svn-id: https://core.svn.wordpress.org/trunk@19538 1a063a9b-81f0-0310-95a4-ce76da25c4cd