Enable section milestones

As far as I understand, you need to enable subsection prerequisites in the course advanced settings:

Then, the prerequisite setting will become visible in the subsection advanced settings:

Note that the “common-env-features” is a JSON-formatted patch, so booleans are written as “true/false” (in lower case) and not as “True/False”:

name: milestone
version: 0.1.0
patches:
  common-env-features: |
    "MILESTONES_APP": true