added skipping challenges

DNS-01-hook-for-DuckDNS.md

@@ -23,10 +23,20 @@ case "$1" in
         curl "https://www.duckdns.org/update?domains=$domain&token=$token&txt=removed&clear=true"
         echo
         ;;
+    "sync_cert")
+        ;;
     "deploy_cert")
         ;;
+    "deploy_ocsp")
+        ;;
     "unchanged_cert")
         ;;
+    "invalid_challenge")
+        ;;
+    "request_failure")
+        ;;
+    "generate_csr")
+        ;;
     "startup_hook")
         ;;
     "exit_hook")