Retire valentyusb and point people to LUNA

[mithro]

It would be good to get any users of ValentyUSB to move towards LUNA which is much better coded and actually maintained.

[mithro]

FYI - @ktemkin

[gaudat]

After struggling with LUNA for a month I can say unless you need high speed USB2 or USB3, ValentyUSB is probably better supported. Since there is an official port of TinyUSB on Valenty's eptri interface, while LUNA's equivalent has been "Not yet supported -- check back soon!" since mid 2021.

I have been trying to port TinyUSB to LUNA in this week but keep running into incompatibilities beyond register locations, and weird behaviors of LUNA's eptri core. It is probably better to take reference to USB peripherals on existing MCUs and try to make a bit-compatible version for LUNA.

Meanwhile I will probably use a microcontroller or FTDI chip if I want an embedded processor on the FPGA to speak USB. You can make LUNA or Valenty work but you can buy maybe a thousand chips with that labor.

/rant