How to enable Secure Websockets transport

[lidel]

We are missing a standalone tutorial with two chapters:

• how to enable WebSockets (/ws) in go-ipfs / js-ipfs
• how to add TLS cert and announce it to other peers as Secure WebSockets (/wss) so it can be used by js-ipfs running in browser.

We have some prior art in https://docs.ipfs.io/how-to/create-simple-chat-app/#ssl-nginx, what remains to be done is to extract relevant info to standalone "How to enable Secure Websockets transport" tutorial and link to it, instead of duplicating content.