Write some deployment instructions into the readme

[aharwood2]

We need some instructions to help deployment. Can we perhaps put this in the readme and draft here?

DRAFT

1. Get a VM, DNS, SSL cert, and CAS / Shib / Entra whitelisting with standard attributed passed back.

2. Setup Deploy Key on GitHub.

3. Install Git (sudo apt install git), Docker, Nginx (sudo apt install nginx)

4. Create directory to store persistent files e.g. the SQLite DB if applicable and keyring information etc. This path needs to match what is passed to Docker compose in the next step.

5. Copy and populate the env file for Docker Compose, by copying the sample in the source code and editing. This can be placed anywhere on the system but needs to be referenced when executing Docker Compose commands (see readme for `--env-file`` argument.

6. Update Nginx reverse proxy config by copying over the snippets in the deployment directory of the source code and adding the appropriate symlink to enable the site.

7. Add the site to the RSE Services DB with a PR (UoM Only)

8. Add a cronjob to do the hourly DB backup by having it execute the db_backup script on the hour.

[aharwood2]

@PhilBradbury -- can you follow this for Goar's machine and test it covers it. I don't want to duplicate what is already in the README so worth seeing how this can integrate as an addition.