add crates.io shields to README as release preparation

the links don't work yet as the crate hasn't been published yet, but
this way they're already present in the README for v0.1.0.

Author: rursprung

README.md

@@ -1,5 +1,7 @@
 # Adafruit Bluefruit LE Connect Controller Protocol Parser
 [![CI](https://github.com/rursprung/adafruit-bluefruit-protocol-rs/actions/workflows/CI.yml/badge.svg)](https://github.com/rursprung/adafruit-bluefruit-protocol-rs/actions/workflows/CI.yml)
+[![Crates.io](https://img.shields.io/crates/v/adafruit-bluefruit-protocol)](https://crates.io/crates/adafruit-bluefruit-protocol)
+![Licenses](https://img.shields.io/crates/l/adafruit-bluefruit-protocol)
 
 This implements the [Adafruit Bluefruit LE Connect controller protocol](https://learn.adafruit.com/bluefruit-le-connect/controller)
 which is e.g. used by the [Adafruit Bluefruit LE UART Friend](https://learn.adafruit.com/introducing-the-adafruit-bluefruit-le-uart-friend).