socket_readmsg() is actually socket_recvmsg()

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@330656 c90b9560-bf6c-de11-be94-00142212c4b1
Rename file

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@330657 c90b9560-bf6c-de11-be94-00142212c4b1