[alfra]

When I look at, for example, technical updates from the Facebook Engineering teams, it's really a little textbook, a distilled version of the knowledge at that point in time.

Same if you bring new team members up to speed by talking to that person.

There is typically no single "historical" document that does the job. Old documents (e-mails, descriptions, comments, ...) tend to be outdated. New documents tend to be increments, so they don't really make sense if you don't know what is written in the old documents.

I expect that in the near future, automatic summaries based on NLP would be able to do all the heavy lifting, so the head of engineering (or whoever is in charge) will only edit the doc, not write it from scratch.