Inline documentation for hooks in wp-admin/includes/update.php.

Props stevenkword for the initial patches.
Fixes #26252.


git-svn-id: https://develop.svn.wordpress.org/trunk@26540 602fd350-edb4-49c9-b593-d223f7449a82
Remove @uses from get_screen_icon() / screen_icon(). see #26119.


git-svn-id: https://develop.svn.wordpress.org/trunk@26541 602fd350-edb4-49c9-b593-d223f7449a82