More verbose message for frontend testing

src/main.c

@@ -42,7 +42,7 @@ int main(void)
 
 	for (unsigned long i = 1;; i++) {
 		if (i >= 99999) i = 1;
-		sprintf(buf, "[CORE] Update #%05lu...\r\n", i);
+		sprintf(buf, "[CORE] Fetching sensors #%05lu...\r\n", i);
 		UART_SendString(buf);
 		_delay_ms(3000);
 	}