update jupyter extension dev mode guidance
update jupyter extension dev mode guidance

nteract/nteract,nteract/nteract,jdfreder/nteract,rgbkrk/nteract,jdfreder/nteract,nteract/nteract,jdfreder/nteract,nteract/composition,nteract/composition,rgbkrk/nteract,jdfreder/nteract,rgbkrk/nteract,rgbkrk/nteract,nteract/composition,rgbkrk/nteract,nteract/nteract,nteract/nteract