add secure headers (#921)

Co-authored-by: Alexander Kartavenko <askemailbox@gmail.com>

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()`
 * [Roave Security Advisories](https://github.com/Roave/SecurityAdvisories) - This package ensures that your application doesn't have installed dependencies with known security vulnerabilities.
+* [Secure Headers](https://github.com/BePsvPT/secure-headers) - A package that adds security related headers to HTTP response.
 * [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.
 * [Zap](https://github.com/zaproxy/zaproxy) - An integrated penetration testing tool for web applications.