Merge branch 'doc/improve-patch-instructions' into 'master'

[solutionchecker] Make pipeline error message for wrong patches more explicit.

See merge request !231

.patches/apply_patches.sh

@@ -20,7 +20,7 @@ do
   then
     echo "The solution for $exerciseName seems to be up to date."
   else
-    echo "You forgot to update the exercise or the solution for $exerciseName!"
+    echo "You forgot to update the exercise or the solution for $exerciseName! Please look at the scripts `.create_all_patches.sh` or `.create_single_patch.sh` and their respective instructions to update the patches which map the exercise state to the solution state. These two shell scripts are hidden files located in the root folder of dumux-course."
     exit 1
   fi
 done