backport doc improvements from Michael Isvy
 `svn merge -c1427704 ^/tiles/framework/trunk`
 http://svn.apache.org/viewvc?view=revision&revision=1427704


git-svn-id: https://svn.apache.org/repos/asf/tiles/framework/branches/TILES_3_0_X@1427705 13f79535-47bb-0310-9956-ffa450edef68