chore: update readme

git-svn-id: https://plugins.svn.wordpress.org/disable-wysiwyg/trunk@1029103 b8457f37-d9ea-0310-8a92-e5e31aec5664
Merge branch 'master' of github.com:sparanoid/disable-wysiwyg

Conflicts:
	disable-wysiwyg.php
	readme.txt

git-svn-id: https://plugins.svn.wordpress.org/disable-wysiwyg/trunk@1029104 b8457f37-d9ea-0310-8a92-e5e31aec5664