DOC: Tighten ecosystem->array libraries (#260)
DOC: Tighten ecosystem->array libraries (#260)

* DOC: Tighten ecosystem->array libraries

Rewriote first sentence, trimmed rest of intro. Partly
brevity, partly because words like "newer" or "modern"
might not be clear.
numpy/numpy.org,numpy/numpy.org,numpy/numpy.org,numpy/numpy.org