This is me.

For example, /srv/docker/synching contains:

compose.yml
.env
./Sync

That last one is a directory bound to the container which contains all my sync folders.

Occasionally it makes more sense to put the mounted folder in /srv like /srv/photos is mounted by /srv/docker/photoprism/compose.yml

However, thats a rarity. Things mostly accessed by a single compose stack are kept alongside the other files for that stack.