small grammar fix (home-assistant#4338)

cogneato · fabaff · commit 298eca2cbf44 · 2018-01-04T20:42:22.000+01:00
diff --git a/source/_addons/duckdns.markdown b/source/_addons/duckdns.markdown
@@ -42,7 +42,7 @@ http:
   ssl_key: /ssl/privkey.pem
 ```
 
-If you use a other port as `8123` or a SSL proxy, change the port number.
+If you use a port other than `8123` or an SSL proxy, change the port number accordingly.
 
 ## {% linkable_title Router configuration %}
 
