Fixes for hooks documentation in wp-admin/admin-footer.php.

Adds some new lines, some hook-line spacing, docs-specific variables, and other language tweaks.

See #26869, #25229, [25252].


git-svn-id: https://develop.svn.wordpress.org/trunk@27145 602fd350-edb4-49c9-b593-d223f7449a82