add documentation

docs/configs/forcings.rst

@@ -9,4 +9,7 @@ conditions. If the model need data during the run (dynamic forcings),
 the forcings will be fetched by default from the same source as the
 input. However, you can specify a different source.
 
+The example below shows an example where the forcings are fetched from
+``mars`` while the initial conditions are fetched from ``test``.
+
 .. literalinclude:: forcings_1.yaml

docs/configs/inputs.rst

@@ -7,7 +7,7 @@
 The input methods listed below are used to fetch the initial conditions
 of a model run. They will also be the source of forcings during the
 model run, unless a ``forcing`` entry is specified in the configuration
-(see :ref:`forcings``).
+(see :ref:`forcings`).
 
 **********
  Datasets