✏ Fix documentation typo in behind a proxy tutorial (#1807)

docs/en/docs/advanced/behind-a-proxy.md

@@ -238,7 +238,7 @@ Now, if you go to the URL with the port for Uvicorn: <a href="http://127.0.0.1:8
 !!! tip
     Notice that even though you are accessing it at `http://127.0.0.1:8000/app` it shows the `root_path` of `/api/v1`, taken from the option `--root-path`.
 
-And now open the URL with the port for Traefik, including the path prefix: <a href="http://127.0.0.1:9999/api/v1/app" class="external-link" target="_blank">http://127.0.0.1:9999/api/vi/app</a>.
+And now open the URL with the port for Traefik, including the path prefix: <a href="http://127.0.0.1:9999/api/v1/app" class="external-link" target="_blank">http://127.0.0.1:9999/api/v1/app</a>.
 
 We get the same response: