@kzimmerman : This topic came up in our steering committee meeting last week. Do you have any suggestions? or preferences?

There is an existing phab task(T361327) that I think relates to this question and highlights the current split of metrics documentation between meta and mediawiki.org. Unfortunately my work in the data domain has focused mostly on the underlying datasets, not metrics derived from them, so I'm not sure I can be of much help here. My main recommendation would be to pick one place and keep it consistent, and add clear cross-references to and from other locations where your audience might expect to find the information. I would lean towards choosing meta over mediawiki.org for this type of content, but even that choice is ambiguous because there's already so much metrics-related content on mw: https://www.mediawiki.org/wiki/Wikimedia_Product/Data_dictionary

thanks @TBurmeister for your inputs . We will park it in meta wiki, per the other suggestions.
Also https://www.mediawiki.org/wiki/Wikimedia_Product/Data_dictionary should be deprecated since we have Datahub now, and this information was pre-datahub. I'll create a task for deprecating, after conferring with other data users. thanks for bringing it up !