Include more info in the readme.txt

git-svn-id: https://plugins.svn.wordpress.org/validated-field-for-acf/trunk@910860 b8457f37-d9ea-0310-8a92-e5e31aec5664
typos in the read me	

git-svn-id: https://plugins.svn.wordpress.org/validated-field-for-acf/trunk@910861 b8457f37-d9ea-0310-8a92-e5e31aec5664