* add --init to suggested docker run invocations
See #2096; this should fix unreaped zombies when using an auth-script or
ip-check-script that spawns its own subprocesses, then exits before reaping
them.
* add a note on why --init
- Environment variable prefix
- DNSBL repo URI
- Project and repo names in link to Docker-specific instructions
- Docker container and volume names in docker run command
-P/--publish-all publishes the container ports on a random
host port, which you have to look up using `docker port`.
In the common case they should be published on the same ports.
