Relocate hook docs so they directly precede the hook lines moved into foreach statements in [30140].

It's necessary for hook docs to directly precede hook lines so the parser can correctly match them up. This change relocates hook docs for `update_{$meta_type}_meta`, `update_postmeta`, `updated_{$meta_type}_meta`, and `updated_postmeta`.

Fixes #11683.


git-svn-id: https://develop.svn.wordpress.org/trunk@30149 602fd350-edb4-49c9-b593-d223f7449a82