feat: expose merge_commit_template to gitops scheduler

[Skisocks]

Changes

• Expose merge_commit_template to scheduler config so github default can be overriden
• Regen docs (picked up some dangling changes)
  • sheduler changes (this PR)
  • pusher-wave -> wave
  • --release-notes-file

Context

We use the merge_method: squash for all our repositories. This work fine aside from github incorrectly inferring a link to the wrong PR in our cluster repos.

1. PR in app repo is squashed with default github message:
   deps: update service docker tag to v1.0.0 (#535)
2. This ends up in the release notes of the app:

Chores
    deps: update service docker tag to v1.0.0 (#535) (some-bot)

3. Which then end up in the PR description when this app is promoted to our cluster repo:

Chores
    deps: update service docker tag to v1.0.0 (#535) (some-bot)

Problem is the #535 in the context of the cluster repo actually points to PR 535 in the cluster repo rather than the app repo.

We'd like to overwrite the default merge commit message at the scheduler level so that the references are correct e.g.:

Chores
    deps: update service docker tag to v1.0.0 (some-org/some-repo#535) (some-bot)

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[Skisocks]

/cc @msvticket