Update docker compose docs to remove reference to nonexistent compose file

[MoralCode]

this line refers to a database-compose.yml that has not existed for at least as long as ive been involved in this project.

CollectOSS/docs/source/docker/docker-compose.rst

Line 53 in 9c7c9f3

docker compose -f docker-compose.yml -f database-compose.yml up

the reference to this should be removed.

This whole file should ideally describe the current process of using docker, which is essentially "use environment.txt as a sample for creating your .env file, then run docker compose up"