[shallowwwater] added dam break description

test/freeflow/shallowwater/problem.hh

@@ -90,7 +90,12 @@ struct EnableGridFluxVariablesCache<TypeTag, TTag::ShallowWaterModel> { static c
  * \ingroup Shallow water equations model
  * \ingroup ImplicitTestProblems
  *
- * \brief A simple dam break test
+ * \brief A simple dam break test (1D wet dam break). 
+ *
+ * The domain is 20 meters long with a gate in the middle. On the left
+ * side the water depth is 4 meters and on the right side the depth is 1 meter.
+ * All boundaries are set to no-flow. 
+ *      
  *
  * This problem uses the \ref ShallowWaterModel
  *