Added docker-compose.yml way of installing

[RexYuan]

I added a docker compose file example to the documentation. Note that the thumbnail directory bind mount is necessary because if it wasn't there already and the content folder isn't writable, it will fail to mkdir the thumb /content/thumb.

[Difegue]

👋 Were you aware of the compose file already located at https://github.com/Difegue/LANraragi/blob/dev/tools/build/docker/docker-compose.yml ? I wonder if this doc change shouldn't mention this file instead.

I think I'll add this extra volume to the main dockerfiles though, we had some discussions about it recently over at #953.

[RexYuan]

Thanks for updating the Dockerfile! As for the dev environment docker-compose.yml, I think it's okay to not mention it here because people won't need it for a simple user setup. Additionally, the first time I found this project I did a search of "docker-compose" in the doc site and the first thing it showed was that file and it was sorta confusing since I wasn't expecting to be reading about the dev environment the first time setting the project up

[siliconfeces]

Yeah that compose file is mostly useful for developers, or if you are peculiar about your container setup and want to keep redis separate.

[Difegue]

Yeah, I suppose it makes sense to include a simple one in the doc. Works for me!

[holopin-bot]

Congratulations @RexYuan, the maintainer of this repository has issued you a holobyte! Here it is: https://holopin.io/holobyte/clxxs2jlc09080dldyw0ywm5w

This badge can only be claimed by you, so make sure that your GitHub account is linked to your Holopin account. You can manage those preferences here: https://holopin.io/account.
Or if you're new to Holopin, you can simply sign up with GitHub, which will do the trick!