board config file for NRF52811

I'm trying to run mynewt for my board with NRF52811(my board schematic [USB_dongle.PDF](https://github.com/apache/mynewt-core/files/4043225/USB_dongle.PDF) ).
As far as I can see, this processor is supported but there is no board for it.

I tried to create a board based on nordic_pca10040 but I must have made a mistake somewhere: my firmware does not run.
I make this conclusion because the blink does not light the LED (I tried to configure the blink led to pin 10 or 9, this is my UART, but there are also two LEDs, you can understand better if you look at the schematic).

Му modifed board: [nrf_52811board.zip](https://github.com/apache/mynewt-core/files/4043204/nrf_52811board.zip)

Could you tell me what I have to do to run the code on NRF52811 processor?
As far as I can see, support for NRF52811 was added by a respected @alvarop. Perhaps you can help me?

Start by comparing the attached nrf_52811board.zip with the nordic_pca10040 board configuration and review the USB_dongle.PDF schematic for the processor, UART, and LED pins. Run the blink firmware with the board configuration and verify that it boots and drives the schematic's LEDs; the board definition should work without the reported pin or startup failure.

Written by the indexing model from the issue text.