Add supported boards mention to board type err

It's better to point the user to more information rather than just throwing a blanket error that says "you can't do that"

Author: dmadison

src/XInput.cpp

@@ -50,7 +50,7 @@
 	#ifdef USB_XINPUT
 		#warning "Unknown board. XInput may not work properly."
 	#else
-		#error "This board does not support XInput!"
+		#error "This board does not support XInput! You must use a USB capable board with the corresponding XInput boards package. See the list of supported boards in the 'extras' folder for more information"
 	#endif
 #endif /* if supported board */