readme.txt fix

git-svn-id: https://plugins.svn.wordpress.org/pta-member-directory/trunk@761811 b8457f37-d9ea-0310-8a92-e5e31aec5664
added help file

git-svn-id: https://plugins.svn.wordpress.org/pta-member-directory/trunk@761812 b8457f37-d9ea-0310-8a92-e5e31aec5664