instructions don't work because there is no bash

[tbradley-sans]

At the bottom of the README.md, there's a note that says this:

Or you can add a sleep time to make sure the hub is ready: docker-compose run --rm webdriverio bash -c "sleep 10 && wdio".

However, since your Dockerfile specifies node:8.9-alpine, there is no bash. So this command gets this error message:

Error response from daemon: OCI runtime create failed: container_linux.go:348: starting container process caused "exec: "bash": executable file not found in $PATH": unknown