Add info how to disable authentication 🔑 (#1428)

* Add info how to disable authentication


Signed-off-by: Sebastian Gerber <github@sgerber.com>

* replaced userdata with wildcard

configuration/restdocs.md

@@ -87,6 +87,18 @@ To authenticate with an API token, **apaddpend `-u '{API_TOKEN}:'` to the comman
 
 You can manage all access tokens in your profile settings in the Main UI.
 
+### Disable authentication
+
+It is possible to disable authentication.
+Stop openhab and add this part to ```$OPENHAB_USERDATA/etc/org.apache.karaf.features.xml``` before ```</featuresProcessing>```:
+
+```
+    <blacklistedFeatures>
+        <feature>openhab-*-auth</feature>
+    </blacklistedFeatures>
+```
+Once openhab is restarted authentication will be disabled.
+
 ## Additional Considerations
 
 The REST API also supports server-push supporting subscriptions on change notification for certain resources.