update documentation

doc/source/appendices/tutorial.rst

@@ -145,4 +145,4 @@ fluff tracer.  Then update the timeseries plotting script to plot the fluffballs
     git checkout columnphysics/icepack_mechred.F90
     git status
 
-**NOTE:** The file, :download:`fluff.diff`, contains code differences for this example using a version of Icepack from July, 2024.  They may not be relevant for the latest code, but provides a sample of the typical code differences required to add the tracer, fluff.
+**NOTE:** The file, **doc/source/tutorial/fluff.diff** in the Icepack repository, contains code differences for this example for a version of Icepack from July, 2024.  They may not be relevant for other code versions, but these diffs provide an example of the typical code differences required to add the tracer, fluff.