Fix #15506 Update documentation for plugins index.md (#15518)

* Update documentation for plugins index.md

You should restart netbox-rq workers if you added a plugin. Otherwise you can't load modules from plugin to custom scripts later.

* Update docs/plugins/index.md

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Co-authored-by: Jeremy Stretch <jstretch@netboxlabs.com>

docs/plugins/index.md

@@ -82,10 +82,10 @@ Plugins may package static files to be served directly by the HTTP front end. En
 
 ### Restart WSGI Service
 
-Restart the WSGI service to load the new plugin:
+Restart the WSGI service and RQ workers to load the new plugin:
 
 ```no-highlight
-# sudo systemctl restart netbox
+# sudo systemctl restart netbox netbox-rq
 ```
 
 ## Removing Plugins