documentation for constructor of pools

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@332927 c90b9560-bf6c-de11-be94-00142212c4b1
moar docs for pool

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@332928 c90b9560-bf6c-de11-be94-00142212c4b1