Add RISC-V badge to README (#336)

* Add RISC-V badge to README

* Fix badge label
Co-authored-by: NAdvait Jain <advaitjain@users.noreply.github.com>

README.md

@@ -39,6 +39,7 @@ Build Type      |    Status     |
 Arduino         | [![Arduino](https://github.com/tensorflow/tflite-micro/actions/workflows/arduino.yml/badge.svg)](https://github.com/tensorflow/tflite-micro/actions/workflows/arduino.yml) [![Antmicro](https://github.com/antmicro/tensorflow-arduino-examples/actions/workflows/test_examples.yml/badge.svg)](https://github.com/antmicro/tensorflow-arduino-examples/actions/workflows/test_examples.yml) |
 Cortex-M        | [![Cortex-M](https://github.com/tensorflow/tflite-micro/actions/workflows/cortex_m.yml/badge.svg)](https://github.com/tensorflow/tflite-micro/actions/workflows/cortex_m.yml) |
 ESP32   | [![ESP32](https://github.com/tensorflow/tflite-micro/actions/workflows/esp32.yml/badge.svg)](https://github.com/tensorflow/tflite-micro/actions/workflows/esp32.yml) |
+RISC-V   | [![RISC-V](https://github.com/tensorflow/tflite-micro/actions/workflows/riscv.yml/badge.svg)](https://github.com/tensorflow/tflite-micro/actions/workflows/riscv.yml) |
 Sparkfun Edge   | [![Sparkfun Edge](https://github.com/tensorflow/tflite-micro/actions/workflows/sparkfun_edge.yml/badge.svg)](https://github.com/tensorflow/tflite-micro/actions/workflows/sparkfun_edge.yml) |
 Xtensa     | [![Xtensa](https://github.com/tensorflow/tflite-micro/actions/workflows/xtensa.yml/badge.svg?event=schedule)](https://github.com/tensorflow/tflite-micro/actions/workflows/xtensa.yml?query=event%3Aschedule) [![Xtensa](https://raw.githubusercontent.com/advaitjain/tflite-micro/local-continuous-builds/tensorflow/lite/micro/docs/local_continuous_builds/xtensa-build-status.svg)](https://github.com/advaitjain/tflite-micro/tree/local-continuous-builds/tensorflow/lite/micro/docs/local_continuous_builds/xtensa.md#summary) |