prom: punt down more complex stuff in tutorial

  [Silencing an alert in advance][] and following

- [Architecture overview][]

- [Alerting philosophy][]

- Where are we in [TPA-RFC-33][], show the various milestones:

  - %"TPA-RFC-33-A: emergency Icinga retirement"

  - %"TPA-RFC-33-B: Prometheus server merge, more exporters"

  - %"TPA-RFC-33-C: Prometheus high availability, long term metrics,

    other exporters"

- If time permits...

- [PromQL primer][]

- [Adding metrics][]

- [How to add alerts][]

- [Queries cheat sheet][]

- [Adding alerts][]

- [Alert debugging][]:

  - Alert unit tests

  - Alert routing tests

  - Ensuring the tags required for routing are there

  - Link to prom graphs from prom's alert page

- Where are we in [TPA-RFC-33][], show the various milestones:

  - %"TPA-RFC-33-A: emergency Icinga retirement"

  - %"TPA-RFC-33-B: Prometheus server merge, more exporters"

  - %"TPA-RFC-33-C: Prometheus high availability, long term metrics, other exporters"

 [Alert debugging]: https://gitlab.torproject.org/tpo/tpa/team/-/wikis/service/prometheus#alert-debugging

 [Queries cheat sheet]: https://gitlab.torproject.org/tpo/tpa/team/-/wikis/service/prometheus#queries-cheat-sheet

 [How to add alerts]: https://gitlab.torproject.org/tpo/tpa/team/-/wikis/service/prometheus#writing-an-alert

 [Adding alerts]: https://gitlab.torproject.org/tpo/tpa/team/-/wikis/service/prometheus#writing-an-alert

 [Adding metrics]: https://gitlab.torproject.org/tpo/tpa/team/-/wikis/service/prometheus#adding-metrics-to-applications

 [Alerting philosophy]: https://gitlab.torproject.org/tpo/tpa/team/-/wikis/service/prometheus#alerting-philosophy

 [Architecture overview]: https://gitlab.torproject.org/tpo/tpa/team/-/wikis/service/prometheus#design