Update browser support for Opera

[zenorocha]

Just started reviewing :)

:octocat: Sent from GH.

[zenorocha]

Hey @mathiasbynens,

Could you add a link to Opera's release announcement for each spec? For example:

• Shadow DOM: http://dev.opera.com/blog/opera-22/
• Custom Elements: http://dev.opera.com/blog/opera-20/

Thanks for updating it :)

[mathiasbynens]

@zenorocha Done. Note that we never announced templates support so I left the original link in there (it’s still a good resource).

[zenorocha]

That's why I couldn't find it :P