update to read me.txt

git-svn-id: https://plugins.svn.wordpress.org/button-maker/trunk@993321 b8457f37-d9ea-0310-8a92-e5e31aec5664
update to read me.txt

git-svn-id: https://plugins.svn.wordpress.org/button-maker/trunk@993325 b8457f37-d9ea-0310-8a92-e5e31aec5664