Doc tweak
Doc tweak

Emphasise Python distribution update for dev installers.

amandersillinois/landlab,SiccarPoint/landlab,csherwood-usgs/landlab,RondaStrauch/landlab,landlab/landlab,cmshobe/landlab,SiccarPoint/landlab,ManuSchmi88/landlab,amandersillinois/landlab,cmshobe/landlab,decvalts/landlab,laijingtao/landlab,RondaStrauch/landlab,ManuSchmi88/landlab,landlab/landlab,Carralex/landlab,cmshobe/landlab,laijingtao/landlab,RondaStrauch/landlab,decvalts/landlab,ManuSchmi88/landlab,Carralex/landlab,csherwood-usgs/landlab,Carralex/landlab,landlab/landlab