Documentation for Firewalled app behind Apache proxy

[rahulsom]

I've wiki-ed it here.
https://github.com/rahulsom/leeroy/wiki/Running-leeroy-behind-an-apache-proxy

I don't think github supports PRs on wikis. You might have to pull it in yourself as shown here.

Or if you prefer I can document it in the README or may be another .md file?

And a big thanks to @joeshaw for guiding me through this.