* Add the Pimoroni Plasma 2040 board
This PR adds the board support package and a simple example.
The example just blinks the on-board RGB LED.
An example should be added for using the board to control an LED strip.
This should probably use smart-leds with the associated PIO driver.
An example or functionality should be added for the current sensor.
* Rename LED data line from dat to data to match schematic
* Add an example for driving WS2812 LEDs
This is pretty much a copy-paste of the awesome pico_ws2812_led example.
* Remove reference in README to rp-pico
* Remove reference to pico board clock speed
I have removed this in the Plasma 2040 repository and where I copied it from, tiny2040_blinky.
* Remove redundant namespace
* Add self-reference in README to the current board's GitHub README
Fix the erroneous link in the pimoroni-tiny2040 README from which I copied.
