README: Clarify bias groups (#110)

Author: Robert Muchsel

README.md

@@ -1,6 +1,6 @@
 # MAX78000 Model Training and Synthesis
 
-_February 11, 2021_
+_February 19, 2021_
 
 The Maxim Integrated AI project is comprised of four repositories:
 
@@ -1558,7 +1558,7 @@ Example:
 
 For layers that use a bias, this key can specify one or more bias memories that should be used. By default, the software uses a “Fit First Descending (FFD)” allocation algorithm that considers largest bias lengths first, and then the layer number, and places each bias in the available group with the most available space, descending to the smallest bias length.
 
-“Available groups” is layer specific and is a list of the groups that have enabled processors for the respective layer. `bias_group` must reference one or more of the available groups.
+“Available groups” is the complete list of groups used by the network (in any layer). `bias_group` must reference one or more of these available groups.
 
 `bias_group` can be a list of integers or a single integer.