Comment about detail on the docs

[ferchaure]

Hi Jeremy, just a comment about the relationship between adjacency_radius and a geometry file with zeros.

The description of the parameter adjacency_radius (on p_ms4alg.py line 31) says:
0 means each channel is sorted independently.

And I thought that was always true. But reading the function get_channel_neighborhood, I understand that even with adjacency_radius=0 all the channels will be sorted together if a geometry with all zeros is used. Maybe a clarification should be included?