Updated readme.

git-svn-id: https://plugins.svn.wordpress.org/floating-social-bar/trunk@907153 b8457f37-d9ea-0310-8a92-e5e31aec5664
More readme updates.

git-svn-id: https://plugins.svn.wordpress.org/floating-social-bar/trunk@907154 b8457f37-d9ea-0310-8a92-e5e31aec5664