Changes

<span style="color:red;">Version 2.5</span>(Updated on Mar. 15th, 2021): use  '''Some fectures:'''* Use the silent PWM cooling fan, and support fan speed is control by script, support read fan speed, and we provide sample ruby code.* Support TRUE AUTO ON function (in the old version,the power management function is disabled if AUTO ON is enabled)* Considering that some customers use X735 together with other DAC shield, and support fan speed is control by script, support read fan speed, and we provide sample ruby codeadjusted the GPIO pins used.