Fix typos concerning hierarchy
Uwe Kleine-König authored

        heirarchical, hierachical -> hierarchical
        heirarchy, hierachy -> hierarchy
Signed-off-by: default avatarUwe Kleine-König <zeisberg@informatik.uni-freiburg.de>
Signed-off-by: default avatarAdrian Bunk <bunk@stusta.de>
1b3c3714