Add fundamental DTrace documentation. The RFC https://wiki.php.net/rfc/dtrace was merged to PHP 5.4.  More examples and non-static probe tracing would be good to add in future

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@331782 c90b9560-bf6c-de11-be94-00142212c4b1