nmod:poss and det:poss

[sylvainkahane]

Following the discussion #1059, I changed the pages nmod:poss and det:poss.
I think that "nmod:poss is only relevant for languages that have a particular construction, such as the possessive construction of English (also called Saxon genitive), that we want to distinguish from other nmod constructions."
And det:poss is just irrelevant and is a confusion with Poss=Yes. I think that the validator must forbid it.

[dan-zeman]

Please do not edit the documentation (nor the treebanks) during the data freeze period.

I just reverted the det:poss edit because it caused errors.