Document how to estimate and set up the WAL files volume size for pyroscope

[Gmerold]

We need to add a pyroscope-worker row in the table here: https://documentation.ubuntu.com/observability/latest/reference/storage/
to provide a sizing recommendation for the specific worker role that holds the WAL (find out which one that is).

[PietroPasotti]

This will likely depend on canonical/tempo-operators#213
Write it in a way that's generic for all the HA charms, and link it from Tempo and Pyroscope's diataxis trees.

[michaeldmitry]

we can add this as part of https://documentation.ubuntu.com/observability/latest/reference/system-requirements/

[PietroPasotti]

we're missing a section pyroscope but tempo is there

[lucabello]

We should discuss with @sed-i how we should address this in the documentation, and where this belongs to.

[lucabello]

1. The open-ended part (calculations) is updating How to evaluate telemetry volume
2. The close-ended (with precise numbers) is obtaining information from the load test and updating the Sizing guide

[PietroPasotti]

We should coordinate with Sina and/or Leon on what kind of setup they used. Was it bare upstream container images, or charmed? VM sizing?...