Doc/mention internal endpoint (#724)

Signed-off-by: Aaron Chong <[email protected]>

README.md

@@ -78,10 +78,16 @@ cd packages/dashboard
 pnpm start
 ```
 
-This starts up the API server which sets up endpoints to communicate with an Open-RMF deployment, as well as begin compilation of the dashboard. Once completed, it can be viewed at [localhost:3000](http://localhost:3000).
+This starts up the API server (by default at port 8000) which sets up endpoints to communicate with an Open-RMF deployment, as well as begin compilation of the dashboard. Once completed, it can be viewed at [localhost:3000](http://localhost:3000).
 
 If presented with a login screen, use `user=admin password=admin`.
 
+Ensure that the fleet adapters in the Open-RMF deployment is configured to use the endpoints of the API server. By default it is `http://localhost:8000/_internal`. Launching a simulation from `rmf_demos_gz` for example, the command would be,
+
+```bash
+ros2 launch rmf_demos_gz office.launch.xml server_uri:="http://localhost:8000/_internal"
+```
+
 ### Optimized build
 
 The dashboard can also be built statically for better performance.