Mention lawnjelly's smoothing add-on in Fixing jitter and stutter

tutorials/misc/jitter_stutter.rst

@@ -40,6 +40,12 @@ time sources (one is processed in the physics step while another is processed in
 improvements to this, from allowing kinematic bodies to be animated in the regular _process loop, to further fixes in the
 frame timer.
 
+.. note::
+
+    You can use physics interpolation to mitigate physics-related jittering.
+    See `lawnjelly's smoothing-addon <https://github.com/lawnjelly/smoothing-addon>`__
+    for an add-on that can be dropped into any project to enable physics interpolation.
+
 Stutter
 -------