readme.txt correction


git-svn-id: https://plugins.svn.wordpress.org/paypal-currency-converter-basic-for-woocommerce/trunk@849411 b8457f37-d9ea-0310-8a92-e5e31aec5664
moved screenshots

git-svn-id: https://plugins.svn.wordpress.org/paypal-currency-converter-basic-for-woocommerce/trunk@849412 b8457f37-d9ea-0310-8a92-e5e31aec5664