Add Fortran unit tests as a separate test to run

This is needed until #1972 is
resolved

doc/.ChangeLog_template

@@ -121,10 +121,15 @@ infrastructure should be run when appropriate, as described below.
 
     clm_pymods test suite on cheyenne - 
 
-  regular tests (aux_clm: https://github.com/ESCOMP/CTSM/wiki/System-Testing-Guide#pre-merge-system-testing):
+  regular tests:
+      - aux_clm: https://github.com/ESCOMP/CTSM/wiki/System-Testing-Guide#pre-merge-system-testing
+      - Fortran unit tests on cheyenne (until https://github.com/ESCOMP/CTSM/issues/1972 is resolved): from src, run:
+          ../cime/scripts/fortran_unit_testing/run_tests.py --build-dir `mktemp -d --tmpdir=. unit_tests.XXXXXXXX`
+
+    aux_clm on cheyenne ------------
+    aux_clm on izumi ---------------
+    Fortran unit tests on cheyenne -
 
-    cheyenne ----
-    izumi -------
 
   fates tests: (give name of baseline if different from CTSM tagname, normally fates baselines are fates-<FATES TAG>-<CTSM TAG>)
     cheyenne ----