HBASE-11171 More doc improvements on block cache options

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1595267 13f79535-47bb-0310-9956-ffa450edef68
HBASE-11076 Update refguide on getting 0.94.x to run on hadoop 2.2.0+ (Gustavo Anatoly)

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1595269 13f79535-47bb-0310-9956-ffa450edef68