docs: migrate to docker compose v2

[SethFalco]

• Replaces references to Docker Compose v1 to Docker Compose v2.
• Fixes a few typos in the README.

Docker Compose v2 has been out for some time, and Docker Compose v1 (docker-compose) no longer receives updates.

From July 2023 Compose V1 stopped receiving updates. It’s also no longer available in new releases of Docker Desktop.

— https://docs.docker.com/compose/

I think it makes sense to push the documentation and commands over to the v2 equivalents now, since this is what most engineers should have installed now.

Related

• Similar to chore: upgrade docs to docker compose v2 nextcloud/cookbook#1772
• Similar to Changed docker-compose -> docker compose juliushaertl/nextcloud-docker-dev#209

[razzeee]

Thanks for looking into this.