First paragraph of the document, says UDN topologies are defined to be of the set: Layer2, Layer3, Localnet.

In the section titled "Creating a UserDefinedNetwork custom resource"  the example footnotes omit Localnet.

The example states: "The topology field describes the network configuration; accepted values are Layer2 and Layer3. Specifying a Layer3 topology type creates a layer 2 segment per node, each with a different subnet. Layer 3 routing is used to interconnect node subnet"

4.17    

Localnet is mentioned only once in the document.    

Localnet topology example will be included.    

UDN is a TP feature in 4.17