Fixed doctest for max_of_link_end_node_values.
Fixed doctest for max_of_link_end_node_values.

Fixed doctest for max_of_link_end_node_values. Note that this method
needs renaming as it only examines active links, not all links.

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