Update link checker script to produce more readable output

.github/helpers/check_urls.sh

@@ -7,17 +7,21 @@ urls=$(grep -oP "(http|ftp|https):\/\/([a-zA-Z0-9_-]+(?:(?:\.[a-zA-Z0-9_-]+)+))(
 
 fail_counter=0
 
+FAILED_LINKS=()
 for item in $urls; do
 #     echo $item  
     filename=$(echo "$item" | cut -d':' -f1)
     url=$(echo "$item" | cut -d':' -f2-)
-    echo "Checking $url from file $filename"
+    echo -n "Checking $url from file $filename"
     if ! curl --head --silent --fail "$url" 2>&1 > /dev/null; then
-        echo "Invalid link in file $filename: $url"
+        echo -e " \033[0;31mNOT FOUND\033[32m\n"
+        FAILED_LINKS+=("$url from file $filename")
         ((fail_counter=fail_counter+1))
     else
-        echo "$url ok"
+        printf " \033[32mok\033[0m\n"
     fi
 done
 
+echo "Failed files:"
+printf '%s\n' "${FAILED_LINKS[@]}"
 exit $fail_counter