docs: updated user guide\advanced

[coopmarshall]

Updated user guide with steps to secure Dispatcharr behind Nginx Proxy Manager

[MotWakorb]

A few things need changes:

1. You should include a minimum version of Nginx Proxy Manager and probably call it out as "Nginx Proxy Manager" each time, not as NPM, because NPM can also mean "node package manager" and node is used in Dispatcharr.

2. Entries like the following will trip up NPM, because checking the box for "Websockets support" creates these already:
   proxy_http_version 1.1; proxy_set_header Upgrade $http_upgrade; proxy_set_header Connection "Upgrade";

3. You should include screenshots since this is a GUI tool. Make it abundantly clear what steps are being taken.

4. I'd include TLS setup as well - I'd argue they should be able to know how to use ACME with their provider of choice, but you can also include TLS setup during the documentation, I'd add that.

[coopmarshall]

@MotWakorb updated the documentation

1. Removed all references to NPM and spelled out everything as Nginx Proxy Manager
2. I've tested it using both websocket support enabled and disabled and have not noticed any issues. Added a disclaimer in the documentation.
3. Added screenshots with redacted domain
4. Added links to installing nginx proxy manager and SSL certs as well as setting up a domain. There are so many options for TLS setup depending on who they purchased the domain from, who hosts their DNS, if they have self signed CA vs. using Lets Encrypt, etc. I'm assuming if they are setting up Dispatcharr they are hopefully able to setup Nginx Proxy Manager as well.

[MotWakorb]

These changes look good, thank you.