Add ModSecurity WAF

ModSecurity is a pretty decent open-source WAF that can be placed in front of applications. Can this be added to this repo? https://modsecurity.org/

Also OWASP updated its cheatsheet series and placed them on Github, these are a good resource as well: https://github.com/OWASP/CheatSheetSeries/tree/master/cheatsheets

***Can I make a pull request that adds 1 or both of these to the repo?

Hi @danehrlich1, I'm including these changes in #53.