Add PHP-Migration https://github.com/monque/PHP-Migration (#397)

README.md

 * [PHP Manipulator](https://github.com/schmittjoh/php-manipulator) - A library for analysing and modifying PHP Source Code.
 * [PHP Mess Detector](https://phpmd.org/) - A library that scans code for bugs, sub-optimal code, unused parameters and more.
 * [PHP Metrics](https://github.com/phpmetrics/PhpMetrics) - A static metric library.
+* [PHP Migration](https://github.com/monque/PHP-Migration) - A static analyzer for PHP version migration.
 * [PHP Parser](https://github.com/nikic/PHP-Parser) - A PHP parser written in PHP.
 * [PHP Refactoring Browser](https://github.com/QafooLabs/php-refactoring-browser) - A command line utility for refactoring PHP code.
 * [PHP Semantic Versioning Checker](https://github.com/tomzx/php-semver-checker) - A command line utility that compares two source sets and determines the appropriate semantic versioning to apply.