Change readme.txt

git-svn-id: https://plugins.svn.wordpress.org/show-stock-quotes/trunk@917671 b8457f37-d9ea-0310-8a92-e5e31aec5664
Updated readme.txt

git-svn-id: https://plugins.svn.wordpress.org/show-stock-quotes/trunk@917676 b8457f37-d9ea-0310-8a92-e5e31aec5664