Updated READMEs for 3.0.0

Change-Id: I4f4a752a019c239f2faea45687779e7407fe25aa
Reviewed-on: http://review.couchbase.org/41079
Tested-by: Cihan Biyikoglu <cihan@couchbase.com>
Reviewed-by: Chris Hillery <ceej@couchbase.com>