Sunsetting Documentation documents the shutting down of the Documentation Beta. I will leave my earlier answer below the line.
I don't think we should overlook the earlier discussion that we had on this in What does Stack Overflow Documentation mean to GIS Stack Exchange?
As nice as it would be to have a GIS specific set of Documentation, it seems like this will still be years away because Stack Overflow Documentation is still in Beta.
Until Allow Documentation in other Stack Exchange communities is implemented, I think that this feature request for GIS specific Documentation will need to have status deferred (i.e. deferred until the "other than Stack Overflow Documentation" request has become status completed).
A very preliminary attempt at posting ArcPy documentation as a topic within the Python Language tag of Stack Overflow Documentation was started 8 months ago but that seems to have stalled.
After those preliminary efforts, my thoughts on ArcPy documentation now focus on trying to encourage ArcPy questions to always include code snippets so that they are not just better focussed but also are more likely to attract answers with code snippets. If nothing else, these should develop a rich body of example code to pull/copy into GIS Documentation later.
It looks like a start has also been made on ArcGIS tag Documentation at Stack Overflow Documentation. That too has an ArcPy topic within it that seems to be unaware of the ArcPy topic within the Python Language tag at Stack Overflow Documentation.
There is also a QGIS tag proposal at Stack Overflow Documentation.
Starts have also been made on tags for Stack Overflow Documentation about:
- OpenLayers 3
- there may be other GIS tags because my search for them has been anything but exhaustive