Currently each code repository has its data collection documented in that tree. So mozilla-central is at https://gecko.readthedocs.io/en/latest/toolkit/components/telemetry/telemetry/ (and some other places), Hello is at https://github.com/mozilla/loop/blob/master/docs/DataCollection.md and so forth. We need to have a maintained "index" of all of these docs from one location, covering all of Firefox (including Android and iOS). The Firefox privacy notice will then link to this index as a starting point. I'm planning on taking this when I get back from PTO.
This seems to have overlap with the structured documentation effort we have for the whole data pipeline in Q3. We are looking to build a common documentation framework (which Rob is driving) that brings together (inclusion or linkage) data pipeline specs, client docs, dataset documentations, analysis/re:dash/... documentation, etc. We should coordinate when you are back.