add comment for why MAX_HULL_POINTS is 42

libraries/shared/src/ShapeInfo.h

@@ -21,6 +21,9 @@
 #include "DoubleHashKey.h"
 
 const float MIN_SHAPE_OFFSET = 0.001f; // offsets less than 1mm will be ignored
+
+// Bullet has a mesh generation util for convex shapes that we used to
+// trim convex hulls with many points down to only 42 points.
 const int MAX_HULL_POINTS = 42;
 
 enum ShapeType {