Added note that Platform Tests are not working

The note was added to the Release Notes

Also fixed bullet lists - they were rendered incorrectly due to missing line breaks
update overview and HA logical setup per review

 * less text and more structure in networking and storage overview
 * more concise Ceph HA description
 * use active voice instead of passive voice
Updated images for docs
Moved the note one level up as Michael requested
Merge pull request #54 from e0ne/png-images

Updated images for docs
Partially added Svetlana's suggested wording.
Changed the section name as Svetlana suggested
Merge pull request #49 from dmitrymex/master

Added note that Platform Tests are not working
Merge pull request #51 from angdraug/ref-arch-overview

update overview and HA logical setup per review
Added documentation for Murano OSTF tests.
Added note about broken OSTF Sanity Tests
Rebased with master