Add Roave Security Advisories

README.md

 * [PHPSecLib](https://phpseclib.sourceforge.net) - A pure PHP secure communications library.
 * [random_compat](https://github.com/paragonie/random_compat) - PHP 5.x support for `random_bytes()` and `random_int()`
 * [RandomLib](https://github.com/ircmaxell/RandomLib) - A library for generating random numbers and strings.
+* [Roave Security Advisories](https://github.com/Roave/SecurityAdvisories) - This package ensures that your application doesn't have installed dependencies with known security vulnerabilities.
 * [Symfony Security Monitoring](https://security.symfony.com/) - A web tool to check your Composer dependencies for security advisories, previously known as "SensioLabs Security Check".
 * [SQLMap](https://github.com/sqlmapproject/sqlmap) - An automatic SQL injection and database takeover tool.
 * [TCrypto](https://github.com/timoh6/TCrypto) - A simple encrypted key-value storage library.