build: support external networks and labeled external network

[iBotPeaches]

Version 2 does not properly handle external/name networks. So our line was misleading in referring to an external network.

There is an active, unclosed bug in docker docker/compose#10797 which in the latest update (4.21.1 (114176)) has caused our containers to fail booting.

network st-internal was found but has incorrect label com.docker.compose.network set to ""

I'm guessing we'll get a hotfix since it seems unlikely that we have to track or workaround this. So if your project fails you might have to remake our network via:

stop docker
docker network rm -f st-internal
docker network create st-internal --label "com.docker.compose.network=default

Bring projects up again. If they fail with:

Error response from daemon: network 9e5f253c7227c37b38b06e05464af10fc511d543dfc6ee518abe615df0142fe4 not found

Run with --force-recreate to re-establish path to new network without data loss.