Updated installation guide. Typos corrected.

git-svn-id: https://plugins.svn.wordpress.org/nomorecaptchas/trunk@912942 b8457f37-d9ea-0310-8a92-e5e31aec5664
Formatting issue 1

git-svn-id: https://plugins.svn.wordpress.org/nomorecaptchas/trunk@912944 b8457f37-d9ea-0310-8a92-e5e31aec5664