Use a docs-specific variable for the `link_category` hook docs in wp-admin/bookmarks-template.php.

See #25364.

Built from https://develop.svn.wordpress.org/trunk@26980


git-svn-id: http://core.svn.wordpress.org/trunk@26857 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Hook docs spacing and standards fixes for wp-admin/includes/ajax-actions.php.

See #25374.

Built from https://develop.svn.wordpress.org/trunk@26981


git-svn-id: http://core.svn.wordpress.org/trunk@26858 1a063a9b-81f0-0310-95a4-ce76da25c4cd