README: Update use statement to reflect current module hierarchy

5cfa836 ("tree-wide: Improve organisation of the tree") rearranged
where types were exposed by the library, so update the README to reflect
that.

Fixes: 5cfa836 ("tree-wide: Improve organisation of the tree")
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>

Author: amboar

README.md

@@ -11,8 +11,9 @@ creates two namespaces in a subsystem with one controller, one PCIe port, and
 one two-wire port. One of the namespaces is attached to the controller:
 
 ```rust
-use nvme_mi_dev::nvme::{
-    ManagementEndpoint, PciePort, PortType, Subsystem, SubsystemInfo, TwoWirePort,
+use nvme_mi_dev::{
+    ManagementEndpoint, PciePort, PortType, Subsystem, SubsystemInfo,
+    TwoWirePort,
 };
 
 async fn nvme_mi<'a>(router: &'a Router<'a>) -> std::io::Result<()> {