update process parameters for DisplacementControlWithDirectionProcess in the arch snapthrough example

Author: matekelemen

structural_mechanics/validation/two_dimensional_circular_truss_arch_snapthrough/source/DispControl/ProjectParameters.json

@@ -66,8 +66,8 @@
             "Parameters"    : {
                 "model_part_name" : "Structure.PrescribedDisplacement_top",
                 "direction"       : "y",
-                "POINT_LOAD_value": -1.0,
-                "PRESCRIBED_DISPLACEMENT_value" : "-39.0*t",
+                "point_load_value": -1.0,
+                "prescribed_displacement_value" : "-39.0*t",
                 "interval"        : [0.0,"End"]
             }
         }],