PRD Release/Product Overview

[Joe Brockmeier]

Hi all,

Have taken a first crack at the Release/Product Overview section of the
PRD.

https://fedoraproject.org/wiki/Cloud_PRD#Release.2FProduct_Overview

Would appreciate more eyeballs and feedback on this section.

One area I was unsure on, the "major release themes" - any thoughts on
what content we're looking for here?