Provide guidance and examples for TLS/SSL Tunneling

[ColinSullivan1]

We've had a few requests in this area. The doc should include a how-to setup for using stunnel, SSL/TLS tunnels, ssh tunnels, etc to bridge NATS over an established TLS connection.

See:

• https://www.geeksforgeeks.org/what-is-ssl-tunneling/
• https://dzone.com/articles/what-is-ssl-tunneling
• https://cheapsslsecurity.com/p/understanding-the-difference-ssl-tunnel-vs-ssh-tunnel/
• https://en.wikipedia.org/wiki/Stunnel
• https://github.com/ghostunnel/ghostunnel

[ripienaar]

https://www.stunnel.org/ is the generally goto tool for this