fix wrong command

README.md

@@ -8,7 +8,7 @@ used in Uberspace.de environments.
 1. Clone Repo, e.g. to `/home/YOURUSERNAME/autoreply-editor`
 2. Create `config.py` and `message.txt` from their sample files
 3. Install requirements: `pip3 install -r requirements.txt --user`
-4. Create web backend on uberspace: `uberspace web backend app.example.com --http --port 5000`
+4. Create web backend on uberspace: `uberspace web backend set app.example.com --http --port 5000`
 5. Create a service in `~/etc/services.d/autoreply-editor.ini`:
 
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