[Feature] Slight improvement to the documentation

[xuedi]

I have searched the existing feature requests to make sure this is not a duplicate request.

• Yes

The feature

I was reading how to map a External Library into immich, i did read:
https://github.com/immich-app/immich/blob/main/docs/docs/guides/external-library.md

Since i have no idea how the docker-compose file work, i had to google quite a bit to find out what is the 'from' and what is the 'into' side of the volume line

maybe add another 3rd example at the end that explains this a bit better:

• /home/user/photos1:/home/user/photos1:ro
• /mnt/photos2:/mnt/photos2:ro
• /home/user/pathInHostFilesystem:/mnt/readOnlyFolderInTheDockerBox:ro

Its just a small thing, if this makes no sense and it just my issue feel free to close

Platform

• Server
• Web
• Mobile

[bo0tzz]

This is standard docker/docker compose knowledge; we try to avoid documenting that sort of thing in our docs, since we'd end up just duplicating the Docker documentation. Thank you for the suggestion though!