refractor into library crate with examples

examples/stm32wle5jc/README.md

@@ -0,0 +1,16 @@
+# stm32wl-subghz examples for STM32WLE5JC
+
+Simple rx/tx examples targeting the STM32WLE5JC chip (tested on LoRa E5-mini board).
+
+## Building and running
+```sh
+cargo build --release
+```
+
+```sh
+cargo run --release
+```
+
+The run command should automatically use `probe-rs` to flash the compiled binary on the microcontroller.
+
+Adjust the board name and targets in `./cargo/config.toml`, `./Cargo.toml` (`embassy-stm32` feature) and `./rust-toolchain.toml` if your board differs.