docs: link to contributing and developers from index
docs: link to contributing and developers from index

willu47/smif,nismod/smif,nismod/smif,willu47/smif,willu47/smif,nismod/smif,tomalrussell/smif,tomalrussell/smif,tomalrussell/smif,willu47/smif,tomalrussell/smif,nismod/smif