Inline documentation for wp-admin/options-reading.php.

Props siobhyb for the initial patch.
Fixes #25430.

Built from https://develop.svn.wordpress.org/trunk@25717


git-svn-id: http://core.svn.wordpress.org/trunk@25630 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Add missing variable for inline hook documentation changes in wp-includes/vars.php.

See #25466.

Built from https://develop.svn.wordpress.org/trunk@25718


git-svn-id: http://core.svn.wordpress.org/trunk@25631 1a063a9b-81f0-0310-95a4-ce76da25c4cd