Added more information about CAPTCHA.

git-svn-id: https://plugins.svn.wordpress.org/cleantalk-spam-protect/trunk@986942 b8457f37-d9ea-0310-8a92-e5e31aec5664
Minor fix.

git-svn-id: https://plugins.svn.wordpress.org/cleantalk-spam-protect/trunk@986943 b8457f37-d9ea-0310-8a92-e5e31aec5664
Minor fix.

git-svn-id: https://plugins.svn.wordpress.org/cleantalk-spam-protect/trunk@986944 b8457f37-d9ea-0310-8a92-e5e31aec5664