DOC: Add ref to handling axis param to permuted
DOC: Add ref to handling axis param to permuted

Made suggested changes to also add Reference on handling of axis parameter
jakirkham/numpy,mhvk/numpy,jakirkham/numpy,pdebuyl/numpy,seberg/numpy,pdebuyl/numpy,pdebuyl/numpy,rgommers/numpy,mattip/numpy,seberg/numpy,charris/numpy,mattip/numpy,jakirkham/numpy,jakirkham/numpy,numpy/numpy,mhvk/numpy,mhvk/numpy,numpy/numpy,anntzer/numpy,seberg/numpy,charris/numpy,mattip/numpy,pdebuyl/numpy,rgommers/numpy,endolith/numpy,anntzer/numpy,mattip/numpy,rgommers/numpy,mhvk/numpy,mhvk/numpy,numpy/numpy,jakirkham/numpy,numpy/numpy,rgommers/numpy,anntzer/numpy,endolith/numpy,charris/numpy,endolith/numpy,anntzer/numpy,seberg/numpy,charris/numpy,endolith/numpy