Readme update

[ErlerPhilipp]

Clarify:

• is ssh_key in secrets really the public key?
• have both workflows in both branches?
• check in deploy script? vars file?
• point by default to deploy.sh instead of start.sh
• single command in readme to create default env file with contents?
• extend certificate section

@akiwa please comment on these ideas / questions

[rieschla]

TODO: describe new HTTP local setup in README

[ErlerPhilipp]

TODO: add address of HTTP test URL (no-cert server available under http://localhost:8082)

[ErlerPhilipp]

also works on windows now. tested without certificate in HTTP mode.
need to check the necessary setup for a clean install. relevant parts include: CUDA toolkit, WSL, Docker Desktop, clone repo, new start script.

[ErlerPhilipp]

document cron job for deleting user data after a while