Better explanation of Rot3 Logmap Lund unit test

gtsam/geometry/tests/testRot3.cpp

@@ -243,10 +243,16 @@ TEST(Rot3, log) {
   Rot3 Rlund(-0.98582676, -0.03958746, -0.16303092,  //
              -0.03997006, -0.88835923, 0.45740671,   //
              -0.16293753, 0.45743998, 0.87418537);
+
+  // Rot3's Logmap returns different, but equivalent compacted
+  // axis-angle vectors depending on whether Rot3 is implemented
+  // by Quaternions or SO3.
   #if defined(GTSAM_USE_QUATERNIONS)
+    // Quaternion bounds angle to [-pi, pi] resulting in ~179.9 degrees
     EXPECT(assert_equal(Vector3(0.264451979, -0.742197651, -3.04098211),
                         (Vector)Rot3::Logmap(Rlund), 1e-8));
   #else
+    // SO3 does not bound angle resulting in ~180.1 degrees
     EXPECT(assert_equal(Vector3(-0.264544406, 0.742217405, 3.04117314),
                         (Vector)Rot3::Logmap(Rlund), 1e-8));
   #endif