add seed to docs

Author: martham93

docs/parameters.rst

@@ -49,7 +49,10 @@ Here is the full list of configuration parameters you can specify in a ``config.
  	``'segmentation'``
  		Output is an array of shape ``(256, 256)`` with values matching the class index label at that position. The classes are applied sequentially according to ``config.json`` so latter classes will be written over earlier class labels if there is overlap.
 
-**split_vals:** list
+**seed**: int
+    Random generator seed. Optional, use to make results reproducible.
+
+**split_vals**: list
     Default: `[0.8, 0.2]`
     Percentage of data to put in each catagory listed in split_names. Must be floats and must sum to one.