Better explain the new autotest

Author: emorway-usgs

autotest/test_gwe_sfe_shf00.py

@@ -1,5 +1,11 @@
 # Test the use of the sensible heat flux utility used in conjuction with the
-# SFE advanced package.  This test is a single cell with a single reach
+# SFE advanced package.  This test is a single cell with a single reach.  
+# Channel flow characteristics are unrealistic: Manning's n is unrealistically
+# low and slope is extremely high. These conditions result in an extremely high
+# streamflow velocity that results in nearly all of the heat being added to the
+# channel exiting at the outlet with very near negligle heat storage increases
+# in the channel.  The result is a 1 deg C rise in temperature in the 
+# streamflow - an easy result to confirm in this test.
 
 import os