Changes

<code>read_fan_speed.py</code> is a sample python file on how to read the speed of the pwm fan. Run the following command to get the speed of the fan:

cd ~x729-script

This `read_fan_speed.py` python file depends on the third-party python library `Rpi.GPIO`. In the official Raspberry Pi OS and most third-party OS, this library is installed by default. If you run this file and get some errors, try to run the following command to install the Rpi.GPIOy library.