Update documentation to use docker compose instead of deprecated docker-compose

[streino]

The latest udata doc at https://udata.readthedocs.io/en/latest/ uses the deprecated docker-compose (v1) command. Compose (v2) now is a plugin of the docker command and should be called with docker compose.

The update should be mostly transparent, but v2 does introduce some changes. For instance, the default container name separator becomes - instead of _. So docker-udata_udata_1 from the Quickstart becomes docker-udata-udata-1.