Document how to host without public DNS

[fuzyll]

This container defaults to 0.0.0.0 for the server, which is great and works well as a default. Unfortunately, having this set causes Ghidra to try and use OpenDNS to figure out what your real public IP is. If you're hosting the service on an intranet with a local DNS resolver, this'll fail miserably because OpenDNS has absolutely no idea how to resolve the hostname.

The issue is trivially fixable by passing the currently-undocumented option -e GHIDRA_IP=your.host.name into the container to override the default of 0.0.0.0, but only if you spend the 45+ minutes I did spelunking around in Wireshark and source code to figure out why it wasn't working.

Thanks for making the container, though!