[DOC] Ideas to improve the Documentation

I commented this point at #1225 . But that issue is about non technical users. This issue is about technical affine admins. So I made a separate issue on the Ideas here.
Following questions and notes arose to me during the study of the README.md:

1. The repository is for the whiteboard app. But the Installation & Setup section only explains how to setup the collaboration function and the communication to the whiteboard collaboration server. May be a note about installing the app itself (app store) would help, and may be the section Installation & Setup should be renamed and divided into two sections "Installing the Whiteboard Collaboration Backend" and "Setup the Communication for Collaboration".
2. Nothing is written about the configuration parameters max_file_size, disable_external_libraries, recording_auto_upload_on_disconnect and legacy_libraries_migrated.
3. In the documentation the whiteboard server (product name) is sometimes called websocket server (technical description) or collaboration server. The occ parameter is called collabBackendUrl . May be it is better understandable to admins, if the whiteboard server is named more consitently - may be "whiteboard collaboration backend".
4. A short note could explain, that the whiteboard collaboration backend" provides a websocket to communicate with the the Webbrowser(s).
5. The URL to address the whiteboard collaboration server is https://..., but it is not described how to configure certificates. Are there (self signed) certificates provided with the whiteboard collaboration backend?
6. For the proxy configuration (Apache, Nginx, Caddy) the url is http:/... .
   Does the whiteboard collaboration server can do both (http and https)?
   Does it support ws://... or wss://... or both?
7. For the proxy configuration, only a ProxyPass (apache), location (nginx) or handle_path (caddy) entry is shown. It would be more clear if it is explicitely noted that the proxy configuration is made in the nextcloud (web) server configuration.
8. All in all it would be helpful to have a communication diagram in the documentation to get a big picture. I could provide a communication diagram if I would understand how the communication flow is.

Start with README.md, especially the Installation & Setup and proxy configuration sections, and review the documented configuration parameters and communication terminology. Clarify which documentation changes are supported by the existing setup, including certificates, HTTP/WebSocket schemes, and proxy placement. Done means the installation, configuration, terminology, proxy guidance, and communication flow are documented consistently, with a diagram if the flow can be established.