Update documentation and example repository for ingestion jobs

[leplatrem]

• https://github.com/leplatrem/remote-settings-cronjob-example/

  1. Move to mozilla org?
  2. Add reusable GH action to publish (see Create a reusable GitHub Actions workflow for ingestion job to publish their container #908) Fix #908: Add reusable workflow to publish ingestion jobs #920
  3. Add Sentry
  4. Switch to uv

• https://remote-settings.readthedocs.io/en/latest/support.html#how-do-i-automate-the-publication-of-records-forever

  1. Update procedure
  2. Simplify specs that are present in the example repo code
  3. Update BZ template
  4. Update links
  5. Maybe turn the whole thing into a dedicated page, with troubleshooting instructions (logs, etc)

• https://mozilla-hub.atlassian.net/wiki/spaces/SRE/pages/834961436/create+a+remote-settings+cronjob+ingestion+pipeline#creating-the-secret

  1. Remove mentions of event router etc.