Update README.md

README.md

@@ -15,7 +15,7 @@ Then start any containers you want proxied with an env var `VIRTUAL_HOST=subdoma
 
     $ docker run -e VIRTUAL_HOST=foo.bar.com  ...
 
-The containers being proxied must [expose](https://docs.docker.com/engine/reference/builder/#expose) the port to be proxied, either by using the `EXPOSE` directive in their `Dockerfile` or by using the `--expose` flag to `docker run` or `docker create`.
+The containers being proxied must [expose](https://docs.docker.com/engine/reference/run/#expose-incoming-ports) the port to be proxied, either by using the `EXPOSE` directive in their `Dockerfile` or by using the `--expose` flag to `docker run` or `docker create`.
 
 Provided your DNS is setup to forward foo.bar.com to the a host running nginx-proxy, the request will be routed to a container with the VIRTUAL_HOST env var set.