Updating compatibility and FAQ to include latest version of WordPress

git-svn-id: https://plugins.svn.wordpress.org/speedcache/trunk@1004761 b8457f37-d9ea-0310-8a92-e5e31aec5664
version updated to 2.0.6

git-svn-id: https://plugins.svn.wordpress.org/speedcache/trunk@1004767 b8457f37-d9ea-0310-8a92-e5e31aec5664