Only add the autosave notice to the first `<h2>` on the page.

Props azaozz. See #24755.

git-svn-id: http://core.svn.wordpress.org/trunk@24710 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Close an HTML tag inside the add_filter() inline doc. props johnbillion, fixes #24772.



git-svn-id: http://core.svn.wordpress.org/trunk@24711 1a063a9b-81f0-0310-95a4-ce76da25c4cd