Add NomadPHP.

README.md

 * [PHP FIG](http://www.php-fig.org/) - The PHP Framework Interoperability Group.
 * [PHP UG](http://php.ug) - A website to help people locate their nearest PHP user group (UG).
 * [Seven PHP](http://7php.com/) - A website that interviews members of the PHP community.
+* [Nomad PHP](http://nomadphp.com/) - A online PHP learning resource.
 
 ## Other Websites
 *Useful websites related to web development.*