Add PHPSpy.

README.md

@@ -417,7 +417,8 @@ Please see [CONTRIBUTING](https://github.com/ziadoz/awesome-php/blob/master/CONT
 * [PHP Console](https://github.com/Seldaek/php-console) - A web debugging console.
 * [PHP Debug Bar](http://phpdebugbar.com/) - A debugging toolbar.
 * [PHPBench](https://github.com/phpbench/phpbench) - A benchmarking Framework.
-* [Tideways.io](https://tideways.com/) - Monitoring and profiling tool
+* [PHPSpy](https://github.com/adsr/phpspy) - A low-overhead sampling profiler.
+* [Tideways.io](https://tideways.com/) - Monitoring and profiling tool.
 * [Tracy](https://github.com/nette/tracy) - A simple error detection, logging and time measuring library.
 * [xDebug](https://github.com/xdebug/xdebug) - A debug and profile tool for PHP.
 * [XHProf](https://github.com/phacility/xhprof) - A profiling tool originally developed by Facebook.