add clarifying comment

Author: PhilDeOrsey

test/boolean-test.ts

@@ -88,7 +88,7 @@ tape('unions', (test) => {
   const union = Polygon.union([u1, u2, u3], undefined, true);
   test.equal(Math.abs(total(union.map(u => u.area)) - (u1.area + u2.area + u3.area)) < 1, true);
 
-  // Using round on these two will produce a zero segment error.
+  // if you change useRound to true on this union it will produce a zero segment error.
   const polyList = [
     new Polygon(new Point(1167.2641162274222, 3633.834721294776), new Point(1342.2641162274222, 3330.7258299702225), new Point(1167.2641162274222, 3330.7258299702225), new Point(1079.7641162274222, 3482.2802756324995)),
     new Polygon(new Point(1692.26, 3936.95), new Point(1342.26, 3936.94), new Point(1254.76, 4088.49), new Point(1079.76, 4088.49), new Point(992.26, 3936.94), new Point(992.27, 3936.94), new Point(1167.26, 3633.83), new Point(1167.2636603221083, 3633.8336603221082), new Point(1342.26, 3330.74), new Point(1517.2542265184259, 3633.84), new Point(1692.26, 3633.84), new Point(1779.76, 3785.39))