Add xmldoc for extension methods
Add xmldoc for extension methods

smoogipooo/osu,NeoAdonis/osu,ppy/osu,UselessToucan/osu,smoogipoo/osu,UselessToucan/osu,ppy/osu,NeoAdonis/osu,NeoAdonis/osu,smoogipoo/osu,peppy/osu,peppy/osu-new,UselessToucan/osu,peppy/osu,ppy/osu,peppy/osu,smoogipoo/osu