minor doc tweaks
minor doc tweaks

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