message: add fully automate dev env screencast into docs
diff: @@ -21,6 +21,8 @@ To get the most out of ephemeral developer environments, it is important to let
  Tasks are shell scripts that run on top of the Docker image you configure (learn more about [custom Docker images](/docs/config-docker)).
  +`youtube: fA2fpqP1xaM`
  +
  ## Execution order
  With Gitpod, you have the following three types of tasks:
  