Correct @param text ordering to put "Optional." in description, see r19019 and...

Correct @param text ordering to put "Optional." in description, see r19019 and #18958. Also remove empty docblock tag.


git-svn-id: https://core.svn.wordpress.org/trunk@19030 1a063a9b-81f0-0310-95a4-ce76da25c4cd