fixed min and max height get coap

src/coap-frontend.cpp

@@ -413,14 +413,14 @@ void CoapFrontend::init_resources(coap_context_t *ctx)
 	m_res_offset = offset;
 
 	//max_height
-	max_height = coap_resource_init((unsigned char *)"max height", 10, COAP_RESOURCE_FLAGS_NOTIFY_CON);
+	max_height = coap_resource_init((unsigned char *)"max_height", 10, COAP_RESOURCE_FLAGS_NOTIFY_CON);
 	s_callbackMap.emplace(max_height, this);
 	coap_register_handler(max_height, COAP_REQUEST_GET, s_get_max_height);
 	coap_add_resource(ctx, max_height);
 	m_res_max_height = max_height;
 
 	//min_height
-	min_height = coap_resource_init((unsigned char *)"min height", 10, COAP_RESOURCE_FLAGS_NOTIFY_CON);
+	min_height = coap_resource_init((unsigned char *)"min_height", 10, COAP_RESOURCE_FLAGS_NOTIFY_CON);
 	s_callbackMap.emplace(min_height, this);
 	coap_register_handler(min_height, COAP_REQUEST_GET, s_get_min_height);
 	coap_add_resource(ctx, min_height);