docstrings changed in histogram in order for the docs to be built correctly
docstrings changed in histogram in order for the docs to be built correctly

lidakanari/NeuroM,eleftherioszisis/NeuroM,mgeplf/NeuroM,liesbethvanherpe/NeuroM,wizmer/NeuroM,BlueBrain/NeuroM,juanchopanza/NeuroM