Fixed typo in doctest.
Fixed typo in doctest.

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