Add project rainbow-hat-rs for support of the Pimoroni Rainbow HAT board

GitHub repo: https://github.com/yannart/rainbow-hat-rs

README.md

@@ -53,6 +53,7 @@ This project is developed and maintained by the [Resources team][team].
     * [Arduino](#arduino)
     * [Nordic](#nordic-2)
     * [NXP](#nxp-2)
+    * [Pimoroni](#pimoroni)
     * [Sparkfun](#sparkfun)
     * [SeeedStudio](#seeedstudio)
     * [SiFive](#sifive-2)
@@ -471,6 +472,11 @@ Crates tailored for specific boards.
 
 [FRDM-KW41Z]: https://www.nxp.com/products/processors-and-microcontrollers/arm-based-processors-and-mcus/kinetis-cortex-m-mcus/w-serieswireless-conn.m0-plus-m4/freedom-development-kit-for-kinetis-kw41z-31z-21z-mcus:FRDM-KW41Z
 
+### Pimoroni
+
+- [`rainbow-hat-rs`](https://crates.io/crates/rainbow-hat-rs) - Board support for the [Pimoroni Rainbow HAT](https://shop.pimoroni.com/products/rainbow-hat-for-android-things) for Raspberry Pi ![crates.io](https://img.shields.io/crates/v/rainbow-hat-rs.svg)
+  - Contains runnable examples for this board
+
 ### Sparkfun
 
 - [`samd21_mini`](https://crates.io/crates/samd21_mini) - Board support for the [SAMD21 Mini Breakout](https://www.sparkfun.com/products/13664) ![crates.io](https://img.shields.io/crates/v/samd21_mini.svg)