Part II of inline documentation for hooks in wp-includes/post.php.

Documents all remaining hooks following [28041] and [28042]. Also updates the hash notation style for `wp_insert_post()`.

Props nacin for several hook descriptions.

Fixes #25376.


git-svn-id: https://develop.svn.wordpress.org/trunk@28106 602fd350-edb4-49c9-b593-d223f7449a82