Hi,
Hope you are doing well. There is no example with that functionality, but you can take this document as a base (Enable I2C Serial Interface in Bluetooth) to enable the SPI interface.
It explains and guides the user to adding an interface to Serial Manager framework. The document is for KW41Z, but it also applies for KW36.
Also, you can refer to section 3.9 "Serial Manager" of the Connectivity Framework Reference Manual.pdf included in the SDK documentation. (Path: SDK_doc.zip\docs\wireless\Common).
Hope this helps.
Best Regards,
Ricardo