SO has a new feature called
Documentations: Does it make sense to have this for plone?
Documentation is broad, and it is a general reference. You aren't documenting a specific problem you're facing, you're helping others deal with an entire class of problems by documenting.
http://docs.plone.org has the same goal. Does it make sense to have this on SO? Of course it's easier to contribute on SO, but maintaining the same content at two places also does not make sense.