Need stronger WARNING on story: Pushing an application using CF API directly

[pstahl-pivotal]

The story Pushing an application using CF API directly is only for advanced students. It has lots of advanced concepts, such as droplets; it requires the student to know whether the package is of type BUILDPACK; and many other things a CF Onboarding participant is unlikely to know.

The current title says "Advanced." This is an inadequate warning. It's the first optional story we encounter, and it won't occur to most students they can skip it. My pair wasted over an hour attempting to do this story before we gave up, frustrated. I suggest either (1) BIG CAPITAL LETTERS and repeating the warning inside the story, and/or (2) moving the story much later in the backlog so it's clear that it's optional.