clarify comment

src/qx_z.erl

@@ -95,8 +95,10 @@ gcd_accum([X | Xs], GCDAccum) ->
 
 -spec gcdabs(znn(), znn()) -> znn().
 % @private gcd where the arguments can be assumed to be non-negative,
-% but not necessarily in the correct order (the argument on the left
-% should be bigger than or equal to the argument on the right).
+% but not necessarily in the correct order
+%
+% This function is responsible for making sure the argument on the
+% left is bigger than or equal to the argument on the right.
 
 gcdabs(X, Y) when X < Y ->
     gcdplus(Y, X);