Add a link to the HZ Grow R502 driver

Author: FLamparski

README.md

@@ -631,6 +631,7 @@ Work in progress drivers. Help the authors make these crates awesome!
 - [ST7735-lcd] - SPI - An embedded-graphics compatible driver for the popular lcd family from Sitronix ![crates.io](https://img.shields.io/crates/v/st7735-lcd.svg)
 - [spi-memory] - SPI - A generic driver for various SPI Flash and EEPROM chips - ![crates.io](https://img.shields.io/crates/v/spi-memory.svg)
 - [st7032i] - I2C - Dot Matrix LCD Controller driver (Sitronix ST7032i or similar). - ![crates.io](https://img.shields.io/crates/v/st7032i.svg)
+- [hzgrow-r502] - UART capacitive fingerprint reader - ![crates.io](https://img.shields.io/crates/v/hzgrow-r502.svg)
 
 [MFRC522]: https://github.com/japaric/mfrc522
 [motor-driver]: https://github.com/japaric/motor-driver
@@ -699,6 +700,7 @@ Work in progress drivers. Help the authors make these crates awesome!
 [ST7735-lcd]: https://crates.io/crates/st7735-lcd
 [spi-memory]: https://github.com/jonas-schievink/spi-memory/
 [st7032i]: https://github.com/dotcypress/st7032i
+[hzgrow-r502]: https://crates.io/crates/hzgrow-r502
 
 ## no-std crates