print sudo command to check failures

src/test/checkInstall

@@ -28,7 +28,7 @@ scripts=("${SOURCE_DIR}/src/scripts/clearvolume.sh" \
 for script in "${scripts[@]}"; do
     if [[ $(sudo -n "${script}" --check 2>/dev/null) != "OK" ]]; then
         echo ""
-        echo "${script} does not have sudo access."
+        echo "${script} does not have sudo access. Try 'sudo -n ${script} --check'"
         echo "You have to add the lines below to /etc/sudoers.d/yellowtent"
         echo ""
         echo "Defaults!${script} env_keep=\"HOME BOX_ENV\""