Add Caddy example

Stateless-Mode.md

@@ -30,6 +30,15 @@ Configure your webserver to respond statelessly to challenges for a given accoun
       }
     }
     ```
+    ### CADDY
+    Add something similar to your `Caddyfile`:
+    ```
+    example.com {
+      @achallenge {
+        path_regexp ch ^/\.well-known/acme-challenge/([-_a-zA-Z0-9]+)$
+     }
+     respond @achallenge "{re.ch.1}.6fXAG9VyG0IahirPEU2ZerUtItW2DHzDzD9wZaEKpqd"
+    ```
     ### APACHE
     Add something similar to your `httpd.conf`:
     ```