fix(uart): Fix mismatch wakeup rising edges required with the threshold configured

Closes https://github.com/espressif/esp-idf/issues/12586

docs/en/api-reference/system/sleep_modes.rst

@@ -326,6 +326,8 @@ When {IDF_TARGET_NAME} receives UART input from external devices, it is often ne
 
 :cpp:func:`esp_sleep_enable_uart_wakeup` function can be used to enable this wakeup source.
 
+After waking-up from UART, you should send some extra data through the UART port in Active mode, so that the internal wakeup indication signal can be cleared. Otherwises, the next UART wake-up would trigger with two less rising edges than the configured threshold value.
+
     .. only:: esp32c6 or esp32h2
 
        .. note::