Update PIO USB docs, fixup used VID/PID macros

[maxgerhardt]

Supersedes #2487

Adds documentation for changing USB VID, PID, manufacturer and product.

Updates used macros.

Confirmed working with

[env]
platform = raspberrypi
framework = arduino
board_build.arduino.earlephilhower.usb_manufacturer = Custom Manufacturer
board_build.arduino.earlephilhower.usb_product = Ultra Cool Product
board_build.arduino.earlephilhower.usb_vid = 0xABCD
board_build.arduino.earlephilhower.usb_pid = 0x1337

[env:picow]
board = rpipicow

[maxgerhardt]

Also just checked with an RP2350 board in ARM and RISC-V mode, both work fine, as does the RP2040 version.