DOC: Note about virtualenv
DOC: Note about virtualenv

Co-authored-by: Matti Picus <faf711dbf9cf26dd81c70c606be887f6131932db@gmail.com>
numpy/numpy,mattip/numpy,endolith/numpy,numpy/numpy,mhvk/numpy,endolith/numpy,endolith/numpy,mattip/numpy,mhvk/numpy,numpy/numpy,charris/numpy,numpy/numpy,mattip/numpy,charris/numpy,mhvk/numpy,mhvk/numpy,endolith/numpy,mhvk/numpy,charris/numpy,charris/numpy,mattip/numpy