Region javadoc link issue

Copied the following from RT-20490:

> Looked into it in b19. All links look good except for this one:
>
> "The full specification is available at css3-background."
>
> I believe the full link should be here instead of just "css3-background".
>
> Could you please fix this?

I'd expect it to be like this:

"The full specification is available at <a>http://www.w3.org/TR/css3-background/&lt;/a>."