Update README.md

[DrFrankensteinUK]

Hi

I amended the Docker section of the Read Me to point at the dedicated Read Me file as the information on the front page does not have the same detailed information or compose information.

I was helping someone with setup on their Synology and completely missed that the compose on the front page is missing the PUID/PGID information vs the actual compose.

Happy to make other amendments if required.