Explain `cut_process` in docs

I was trying to use `ts.statistics.cut_edges_by_weight` and I got a bit confused by the `cut_process` argument [here](https://github.com/microsoft/topologic/blob/da0440722e928c60cfd1919aa9d4b9390f7be962/topologic/statistics/edge_weights.py#L59) - figured it out, but seems worth explaining in the docstring for this function. Could these be string arguments as well?