Document what to look out for for new apps

[badboy]

With the recent treeherder addition I noticed that we don't really have good documentation around what happens for those new applications.

It should be all automated. But sometimes things break. But how does a data engineer verify it worked? How do they identify issues causes by the new product vs potential outside issues (that just got triggered by this)? How to identify missing data because the CI task is missing vs missing data because of other failures?

It might be worthwhile to think about failure cases and document them.

User docs are here: https://mozilla.github.io/glean/book/user/adding-glean-to-your-project/enable-data-ingestion.html We have generic gotchas documented here: https://github.com/mozilla/probe-scraper/blob/main/docs/common-failures.md