Update documentation for Vector2Angle (#4556)

src/raymath.h

@@ -328,8 +328,9 @@ RMAPI float Vector2DistanceSqr(Vector2 v1, Vector2 v2)
     return result;
 }
 
-// Calculate angle between two vectors
-// NOTE: Angle is calculated from origin point (0, 0)
+// Calculate the signed angle from v1 to v2, relative to the origin (0, 0).
+// NOTE: In Raylib's 2D coordinate system (positive X right, positive Y down),
+//       positive angles appear clockwise, and negative angles appear counterclockwise.
 RMAPI float Vector2Angle(Vector2 v1, Vector2 v2)
 {
     float result = 0.0f;