README: Document available branches and tags
README: Document available branches and tags

Change-Id: I3c8a12150db20bbfb700e82edbd86e062493d3f3

chadversary/deqp,chadversary/deqp,chadversary/deqp,chadversary/deqp,chadversary/deqp,chadversary/deqp