examples/rust-gcoap: Add CoAP SAUL demo from module examples

examples/rust-gcoap/Makefile

@@ -19,9 +19,13 @@ USEMODULE += ztimer_usec
 USEMODULE += ztimer_msec
 USEMODULE += ztimer_sec
 
+# for the "vfs" feature of riot-coap-handler-demos (and vfs.c)
 USEMODULE += vfs
 USEMODULE += constfs
 
+# for the "saul" feature of riot-coap-handler-demos
+USEMODULE += saul_default
+
 # Comment this out to disable code in RIOT that does safety checking
 # which is not needed in a production environment but helps in the
 # development process:

examples/rust-gcoap/src/lib.rs

@@ -22,6 +22,7 @@ fn main() {
     let handler = coap_message_demos::full_application_tree(None)
         .below(&["ps"], riot_coap_handler_demos::ps::ps_tree())
         .below(&["vfs"], riot_coap_handler_demos::vfs::vfs("/const"))
+        .below(&["saul"], riot_coap_handler_demos::saul::SaulHandler::new(&["saul"]))
         .with_wkc()
         ;
     let mut handler = riot_wrappers::coap_handler::GcoapHandler(handler);