Documentation does not work for github merge queue

This tutorial leaves out an important step that the enables "merge_group" webhook events.

https://buildkite.com/docs/tutorials/github-merge-queue

See github's documentation that says your CI needs to have merge_group with the type checks_requested.

https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#merge_group

Additionally, enabling `Skip builds with existing commits` is a bad suggestion for pipelines that run certain jobs only on the main branch. I.e. anything that is triggered after the PR submits won't trigger with this setting on and using merge queue.

Lastly, buildkite's internal documentation for setting up github integrations tells the user to set up the webhook without "merge_group".


Start with the GitHub merge queue tutorial and the internal GitHub integration setup documentation, then compare their webhook and workflow guidance with GitHub's merge_group documentation. Done means the tutorial explains the required merge_group/checks_requested event, the guidance about skipping builds with existing commits is corrected, and the integration setup includes merge_group.

Written by the indexing model from the issue text.