Add link to HW selection

Author: andy31415

README.md

@@ -20,3 +20,11 @@ $ cargo install espmonitor
 
 $ cargo generate --vcs none --git https://github.com/esp-rs/esp-idf-template cargo
 ```
+
+## Hardware
+
+This is based on a [EPS32 C3 Series](https://www.espressif.com/en/products/devkits) device:
+
+- C3 Risc-V boards from [AliExpress](https://www.aliexpress.com/wholesale?SearchText=ESP32-C3)
+- SSD1306-based OLED display from [AliExpress](https://www.aliexpress.com/wholesale?SearchText=ssd1306+oled+128x64)
+