Mastodon with Docker rootless, compose, and Nginx reverse proxy

I've written down how I set up my Mastodon server here. This includes some topics that seem not well covered currently:

- use nginx reverse proxy with the official nginx.conf [1], but with some changes needed for compatibility with docker

- use rootless docker, for security, together with bind mounts, for maintainability

- use compose, with some modifications to the official docker-compose.yml [2] that make life easier and are compatible with the reverse proxy

[1]: https://github.com/mastodon/mastodon/blob/main/dist/nginx.co...

[2]: https://github.com/mastodon/mastodon/blob/main/docker-compos...