chore: add release docs

RELEASE.md

@@ -0,0 +1,59 @@
+# RELEASE.md
+
+This document outlines the process for releasing Embassy crates using `cargo-release` and the `release/bump-dependency.sh` script.
+
+When releasing a crate, keep in mind that you may need to recursively release dependencies as well. 
+
+## Prerequisites
+
+- Install [`cargo-release`](https://github.com/crate-ci/cargo-release):
+
+  ```sh
+  cargo binstall cargo-release
+```
+
+## Crate release
+
+Check if there are changes to the public API since the last release. If there is a breaking change, follow
+the process for creating a minor release. Otherewise, follow the process for creating a new patch release.
+
+Keep in mind that some crates may need the --features and --target flags passed to cargo release. For more information on that,
+look at the `Cargo.toml` files.
+
+### Patch release (no breaking public API changes)
+
+```
+cd embassy-nrf/
+cargo release patch --features time,defmt,unstable-pac,gpiote,time-driver-rtc1,nrf52840 --target thumbv7em-none-eabi
+
+# If dry-run is OK (no missing dependencies on crates.io) 
+cargo release patch --execute --features time,defmt,unstable-pac,gpiote,time-driver-rtc1,nrf52840 --target thumbv7em-none-eabi
+```
+
+### Minor release
+
+```
+# Bump versions in crate files
+./release/bump-dependency.sh embassy-nrf 0.4.0
+
+# Commit version bump
+git commit -am 'chore: update to `embassy-nrf` v0.4.0'
+
+# Release crate
+cd embassy-nrf/
+cargo release minor --features time,defmt,unstable-pac,gpiote,time-driver-rtc1,nrf52840 --target thumbv7em-none-eabi
+
+# If dry-run is OK (no missing dependencies on crates.io) 
+cargo release minor --execute --features time,defmt,unstable-pac,gpiote,time-driver-rtc1,nrf52840 --target thumbv7em-none-eabi
+```
+
+## Push tags
+
+Push the git tags that `cargo release` created earlier:
+
+```
+git push --tags
+```
+## Reference
+
+* [PR introducing release automation](https://github.com/embassy-rs/embassy/pull/4289)