fix return types

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@333596 c90b9560-bf6c-de11-be94-00142212c4b1
improve the intro

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@333597 c90b9560-bf6c-de11-be94-00142212c4b1