Add/Adjust Selfhosted install instructions for use behind existing reverse-Proxies

[Ruakij]

Hello,
I'd like to adjust the installation for selfhosted setups once i have adjusted it for my setup.

The current install assumes port 80, 443, 10000 and 33073 are free, which is not the case for many setups.
It also assumes Netbird should get its own Certificate through letsencrypt instead of accepting cert-files as alternative.

For that i have some questions:

1. What protocol does the management service use, looking at the port I assume HTTP?
2. What protocol does the signal system use?
3. Whats is wiretrustee/dashboard being used for? Their docker-page says "This image is not ready for production use"?

Also not 100% sure if i am really willing to rewrite all that to fit my setup without really knowing if netbird works for what i need.
Netmaker was easier to adjust.