docs/run-an-instance: remove mention of "web" in composefile

this has not been relevant for a while now

docs/run-an-instance.md

@@ -18,7 +18,7 @@ if you need help with installing docker, follow *only the first step* of these t
     ```
     i'm using `nano` in this example, it may not be available in your distro. you can use any other text editor.
 
-3. copy and paste the [sample config from here](examples/docker-compose.example.yml) for either web or api instance (or both, if you wish) and edit it to your needs.
+3. copy and paste the [sample config from here](examples/docker-compose.example.yml) and edit it to your needs.
     make sure to replace default URLs with your own or cobalt won't work correctly.
 
 4. finally, start the cobalt container (from cobalt directory):