docs: document github webhooks

Dependencies

• [2] FUOOHCAA Init a docs section for monitoring, document queue-runner-status and the prometheus metrics
• [*] 3JXCTKEC Add markdown files for documentation

Change contents

• edit in doc/manual/src/SUMMARY.md at line 11
  [4.290]

  [2.0]
  + - [Webhooks](webhooks.md)
• file addition: webhooks.md (----------)
  [4.99]
  + # Webhooks

  +

  + Hydra can be notified by github's webhook to trigger a new evaluation when a

  + jobset has a github repo in its input.

  + To set up a github webhook go to `https://github.com/<yourhandle>/<yourrepo>/settings` and in the `Webhooks` tab

  + click on `Add webhook`.

  +

  + - In `Payload URL` fill in `https://<your-hydra-domain>/api/push-github`.

  + - In `Content type` switch to `application/json`.

  + - The `Secret` field can stay empty.

  + - For `Which events would you like to trigger this webhook?` keep the default option for events on `Just the push event.`.

  +

  + Then add the hook with `Add webhook`.