Add note on changed interface

doc.zih.tu-dresden.de/util/check-links.sh

@@ -100,7 +100,6 @@ function check_changed_files(){
 # Make use of the html-proofer-plugin and build documentation
 function check_all_files_hpp() {
   export ENABLED_HTMLPROOFER=true
-  echo "Info: Building documentation and checking internal and external links. Might take some time."
   # Switch for wikiscript
   if [[ -d "doc.zih.tu-dresden.de" ]]; then
     cd doc.zih.tu-dresden.de
@@ -117,20 +116,27 @@ if [[ $# -ge 1 ]]; then
   ;;
   -a | --all)
     export ENABLED_HTMLPROOFER_EXTERNAL_URLS=true
+    echo "Info: Building documentation and checking internal and external links. Might take some time."
     check_all_files_hpp
   ;;
   -i | --internal)
     export ENABLED_HTMLPROOFER_EXTERNAL_URLS=false
+    echo "Info: Building documentation and checking internal links. Might take some time."
     check_all_files_hpp
   ;;
   -c | --changed)
+    echo "Info: Checking links in modified files."
     check_changed_files
   ;;
   *)
+    echo "Info: Checking links in file $1"
     check_single_file "$1"
   ;;
   esac
 else
+  echo -e "Remark: The script changed in Oct. 2024. You did not provide any option.
+        If you intend to check the links of all modified files, please
+        provide the option \"-c\"\n"
   usage
   exit 1
 fi