DOC: Update broken link to diataxis framework.
DOC: Update broken link to diataxis framework.

mattip/numpy,numpy/numpy,endolith/numpy,mattip/numpy,endolith/numpy,charris/numpy,endolith/numpy,charris/numpy,mattip/numpy,charris/numpy,numpy/numpy,numpy/numpy,endolith/numpy,charris/numpy,numpy/numpy,mattip/numpy