HBASE-9406 Document 0.96 migration

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1519155 13f79535-47bb-0310-9956-ffa450edef68
Another edit of how to create a release candiate section

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1519157 13f79535-47bb-0310-9956-ffa450edef68