add "AntiXSS | Protection against Cross-site scripting (XSS) via PHP"

-> https://github.com/voku/anti-xss

README.md

 ### Security
 *Libraries for generating secure random numbers, encrypting data and scanning for vulnerabilities.*
 
+* [AntiXSS](https://github.com/voku/anti-xss) - A library that tries to preventing Cross-Site Scripting (XSS) attacks by blacklisting.
 * [Halite](https://paragonie.com/project/halite) - A simple library for encryption using [libsodium](https://github.com/jedisct1/libsodium).
 * [HTML Purifier](https://github.com/ezyang/htmlpurifier) - A standards compliant HTML filter.
 * [IniScan](https://github.com/psecio/iniscan) - A tool that scans PHP INI files for security.