fix the coupled tutorial after holger's alpha->lambda renaming

git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@5527 2fb0f335-1f38-0410-981e-8018bf24f1b0

tutorial/tutorialspatialparameters_coupled.hh

@@ -113,7 +113,7 @@ public:
 
         //parameters of Brooks & Corey Law
         materialParams_.setPe(500.0);
-        materialParams_.setAlpha(2);
+        materialParams_.setLambda(2);
     }
 
 private: