@spec generate(Mix.Release.t()) :: Mix.Release.t()

Release step that generates appup files and copies them into the release.

Meant to be plugged into a release's :steps, after :assemble:

releases: [
  my_app: [
    steps: [:assemble, &Jellyfish.generate/1, :tar]
  ]
]

It runs the compile.gen_appup and compile.copy_appup Mix compiler tasks for the release's app and its production dependencies, then copies the freshly assembled .rel file into the release's releases/ directory. Returns the given release unchanged, as required by the :steps contract.