docs(mqtt): add "recommended" to Kconfig to tell users that IBM-MQTT will be removed at v4.0
docs(mqtt): add "recommended" to Kconfig to tell users that IBM-MQTT will be removed at v4.0

espressif/ESP8266_RTOS_SDK,espressif/ESP8266_RTOS_SDK,espressif/ESP8266_RTOS_SDK,espressif/ESP8266_RTOS_SDK,espressif/ESP8266_RTOS_SDK