Update README.md - Add Observer

Adds Observer, an offline multi-language security/production-health scanner (MIT). Repo: https://github.com/sanks205/getobserver

README.md

@@ -358,6 +358,7 @@ Please see [CONTRIBUTING](https://github.com/ziadoz/awesome-php/blob/master/CONT
 
 * [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).
+* [Observer](https://github.com/sanks205/getobserver) - An offline CLI that scans a codebase for security & production-health issues and outputs one HTML report (multi-language, dependency CVEs, single binary).
 * [Optimus](https://github.com/jenssegers/optimus) - Id obfuscation based on Knuth's multiplicative hashing method.
 * [OWASP](https://owasp.org/) - Explore the world of cyber security.
 * [PHPGGC](https://github.com/ambionics/phpggc) - A library of PHP unserializable payloads along with a tool to generate them.