[t] (1) rel=external is more an annotation than a hyperlink
Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=25688

git-svn-id: http://svn.whatwg.org/webapps@8635 340c8d12-0b0e-0410-8428-c7bf67bfef74
[e] (0) Adjust examples in <iframe> section to increase diversity

git-svn-id: http://svn.whatwg.org/webapps@8636 340c8d12-0b0e-0410-8428-c7bf67bfef74
[e] (0) Typo in canvas section
Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=25672

git-svn-id: http://svn.whatwg.org/webapps@8637 340c8d12-0b0e-0410-8428-c7bf67bfef74