* add single pool based poller for php-fpm
* add the page for php-fpm
* add graph for php-fpm
* I agree to the conditions of the Contributor Agreement contained in doc/General/Contributing.md.
* use named OID as suggest by @laf
* document PHP-FPM monitoring
* link it in the index
* clean up the named oid
* add how to grab the script in question
