[Ring] Links to source code

[Julian Foad]

A bug report:

  The links to the source code are broken in the FAQ "How to access 
Ring source code?", section "GIT repositories URI on Gerrit". They lead 
to "Not found" errors.

An enhancement request:

  Because it is an open source project, we should display the links to 
the source code prominently on the main pages of the web site, not just 
in a FAQ. We should be able to find the source code through the 
"Download" and "Contribute" sections of the web site.

Thank you.
- Julian