Add docs for metadata (context) in Sidekiq logs
It was discussed at https://docs.google.com/document/d/13TW4x3ofw0RxifZvZ7eNvrPxFnnXmhzQ8fal3fhYgjg/edit that would be interesting for developers and overall understanding of gitlab-org/gitlab!20791 (merged) to have docs around that answering the questions:
- How we add new fields to the context / metadata for Sidekiq
- How to manipulate the context while running (I assume we'd want to document the components involved e.g. classes, middlewares)
Edited by Oswaldo Ferreira