[e] (0) Add some explanatory notes to <optgroup>
Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=25112
Affected topics: HTML

git-svn-id: http://svn.whatwg.org/webapps@8611 340c8d12-0b0e-0410-8428-c7bf67bfef74
[e] (0) Remove the <img> stuff so that zcorpan can edit it instead. (this is purely editorial)
Affected topics: HTML

git-svn-id: http://svn.whatwg.org/webapps@8612 340c8d12-0b0e-0410-8428-c7bf67bfef74