[Exercise][dunemodule] Change text in README.md from advising to copy...

[Exercise][dunemodule] Change text in README.md from advising to copy not-any-more-existing test to existing test.

exercises/exercise-dunemodule/README.md

@@ -41,7 +41,7 @@ The following command will configure your new module
 mkdir appl
 ```
 
-* Copy some test case from the dumux module, e.g. test_box1p
+* Copy some test case from the dumux module, e.g. test_1pfv
     * Copy the problem, spatialparams, cc source file, input file
 
 * Adjust the CMakeLists.txt file to include your new subdirectory
@@ -49,11 +49,11 @@ mkdir appl
 * Add a new CMakeLists.txt in the folder `appl` with the content
 
 ```cmake
-# add a new box 1p test
-add_dumux_test(test_box1p test_box1p test_box1p.cc test_box1p)
+# add a new finite volume 1p test
+add_dumux_test(test_1pfv test_1pfv test_1pfv.cc test_1pfv)
 
 # link the input file to the build folder
-dune_symlink_to_source_files(FILES test_box1p.input)
+dune_symlink_to_source_files(FILES test_1pfv.input)
 ```
 
 * Reconfigure your module by running in the topmost directory of your new module
@@ -68,7 +68,7 @@ cmake build-cmake
 cd build-cmake
 make build_tests
 cd appl
-./test_box1p
+./test_1pfv
 ```
 
 <hr><br><br>
@@ -89,4 +89,4 @@ on our GitLab instance as long as it is DuMuX related.
 **Important**: Before executing the `git add .` command, you should add your cmake build folder to `.gitignore`.
 The easiest way to do so is to copy the `.gitignore` file from the dumux module into your module path. If everything
 worked, executing `git status` should not show `build-cmake` anymore. Never put your executables or other build files
-under version control. Only source files (`*.hh`, `*.cc`, `*.input`, `CMakeLists.txt`) should be under version control.
\ No newline at end of file
+under version control. Only source files (`*.hh`, `*.cc`, `*.input`, `CMakeLists.txt`) should be under version control.