Wrong documentation of colors of SEN0337

The color of the cable of SEN0337 are in order Red, Black, Blue, Green and this corresponds to V+, GND, RX, TX.

In https://wiki.dfrobot.com/sen0337/#tech_specs and https://wiki.dfrobot.com/sen0337/docs/19659 are black and red inverted.

Fortunately, the sensor looks that it's resistant to inverted polarity.