Document Supported USB Serial chips

I spend several days trying to flash a TLSR8253 board with a broken firmware using several USB serial bridges with different chips: Silabs CP2102, FTDI ft232 and Microchip MCP2200. And none worked.

I have had to repurpose a CH340G from a ESP32 board to be able to update the firmware on a TLSR8253 board. It worked the first time.

I think it will be worth adding a note to the webpage saying the USB serial chips that work.