feat: embassy-boot for rp2040

Add embassy-boot support for RP2040, with examples for the Raspberry Pi
Pico.

Co-authored-by: Mathias Koch <mk@blackbird.online>

embassy-boot/rp/README.md

@@ -0,0 +1,26 @@
+# embassy-boot-rp
+
+An [Embassy](https://embassy.dev) project.
+
+An adaptation of `embassy-boot` for RP2040.
+
+NOTE: The applications using this bootloader should not link with the `link-rp.x` linker script.
+
+## Features
+
+* Configure bootloader partitions based on linker script.
+* Load applications from active partition.
+
+## Minimum supported Rust version (MSRV)
+
+`embassy-boot-rp` requires Rust nightly to compile as it relies on async traits for interacting with the flash peripherals.
+
+## License
+
+This work is licensed under either of
+
+- Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or
+  <http://www.apache.org/licenses/LICENSE-2.0>)
+- MIT license ([LICENSE-MIT](LICENSE-MIT) or <http://opensource.org/licenses/MIT>)
+
+at your option.