Fix up the doc of 'dfs.client.read.shortcircuit.buffer.size'

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1591492 13f79535-47bb-0310-9956-ffa450edef68
HBASE-11077 [AccessController] Restore compatible early-out access denial

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1591524 13f79535-47bb-0310-9956-ffa450edef68