#2826: Add config documentation to user guide

doc/psyad/user_guide/psyad_command.rst

@@ -62,7 +62,7 @@ by the command:
 .. parsed-literal::
 		
   >>> psyad -h
-    usage: psyad [-h] [-oad OAD] [-v] [-t] [-api API] [-coord-arg COORD_ARG] [-panel-id-arg PANEL_ID_ARG] [-otest TEST_FILENAME] -a ACTIVE [ACTIVE ...] -- filename
+    usage: psyad [-h] [-oad OAD] [-c CONFIG] [-v] [-t] [-api API] [-coord-arg COORD_ARG] [-panel-id-arg PANEL_ID_ARG] [-otest TEST_FILENAME] -a ACTIVE [ACTIVE ...] -- filename
 
     Run the PSyclone adjoint code generator on a tangent-linear kernel file
 
@@ -73,6 +73,8 @@ by the command:
       -h, --help            show this help message and exit
       -a ACTIVE [ACTIVE ...], --active ACTIVE [ACTIVE ...]
                             name of active variables
+      -c CONFIG, --config CONFIG
+                            config file with PSyclone specific options
       -v, --verbose         increase the verbosity of the output
       -t, --gen-test        generate a standalone unit test for the adjoint code
       -api API              the PSyclone API that the TL kernel conforms to (if any)