Make the example match the documentation
the missing `driver` made my bridge not have the correct MTU when i copied from the example and not the doc table.  Brings them into alignment.
@@ -211,7 +211,7 @@ is also available when creating the ingress network, besides the `--attachable`
$ docker network create -d overlay \
--subnet=10.11.0.0/16 \
--ingress \
- --opt com.docker.network.mtu=9216 \
+ --opt com.docker.network.driver.mtu=9216 \
--opt encrypted=true \
my-ingress-network
```
