fixup! USBUS: add minimal working example

examples/usbus_minimal/Makefile

@@ -14,7 +14,18 @@ DEVELHELP ?= 1
 
 USEMODULE += usbus
 
+# USB device vendor and product ID
+USB_VID ?= 1209
+USB_PID ?= 0001
+
 # Change this to 0 show compiler invocation lines by default:
 QUIET ?= 1
 
+CFLAGS += -DUSB_CONFIG_VID=0x$(USB_PID) -DUSB_CONFIG_PID=0x$(USB_VID)
+
 include $(RIOTBASE)/Makefile.include
+
+ifeq ($(USB_VID):$(USB_PID), 1209:0001)
+  $(shell $(COLOR_ECHO) "$(COLOR_RED)Private testing pid.codes USB VID/PID used!, do not use it outside of test environments!$(COLOR_RESET)" 1>&2)
+  $(shell $(COLOR_ECHO) "$(COLOR_RED)MUST NOT be used on any device redistributed, sold or manufactured, VID/PID is not unique!$(COLOR_RESET)" 1>&2)
+endif

examples/usbus_minimal/README.md

@@ -1,7 +1,7 @@
 # usbus_minimal example
 
 This is a minimalistic example for RIOT's USB stack. The application will
-initialize and start the USB stack. the stack is started without any USB
+initialize and start the USB stack. The stack is started without any USB
 handlers, it should show up as an empty USB device on the host.
 
 RIOT doesn't own any USB vendor and product ID. To compile this example, add