Adding version 1.5.3

git-svn-id: https://plugins.svn.wordpress.org/table-of-contents-generator/trunk@979676 b8457f37-d9ea-0310-8a92-e5e31aec5664
Fixed readme.txt file

git-svn-id: https://plugins.svn.wordpress.org/table-of-contents-generator/trunk@979677 b8457f37-d9ea-0310-8a92-e5e31aec5664