Adjust names of generated files

src/02-basic-grid-interface.cc

@@ -67,7 +67,7 @@ int main(int argc, char** argv)
 
     using GridView = decltype(gridView);
     Dune::VTKWriter<GridView> vtkWriter(gridView);
-    vtkWriter.write("01-refined-grid");
+    vtkWriter.write("02-basic-grid-interface");
 
     return 0;
   }

src/03-function-integration.cc

@@ -104,7 +104,7 @@ int main(int argc, char** argv)
 
     using GridView = decltype(gridView);
     Dune::VTKWriter<GridView> vtkWriter(gridView);
-    vtkWriter.write("01-refined-grid");
+    vtkWriter.write("03-function-integration");
 
     return 0;
   }