message: document that the one-liner starts a new container
diff: @@ -167,7 +167,11 @@ If you want to explore or edit database manually, you can connect to the databas
  with the `psql` command.
  ```sh
  +# NOTE: this creates a new container that will keep running after you exit
  +# To remove the new container, run `docker-compose down`.
  docker exec -it "$(docker-compose run -d db && sleep 1)" psql -U cratesfyi
  +# You only need to start the container once, in the future you can attach to it like so:
  +docker exec -it "$(docker container ps | grep postgres | cut -d ' ' -f 1)" psql -U cratesfyi
  ```
  The database contains a blacklist of crates that should not be built.
  