docs: add release instructions (#228)

RELEASE.md

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+## Release Process
+
+The release process for this repository leverages [`release-plz`](https://github.com/MarcoIeni/release-plz) to automate some of the steps. Only maintainers with the necessary permissions can release new versions of this repository.
+
+1. Install `release-plz`: One option is by running `cargo install --locked release-plz`
+1. Checkout the latest code on `main` branch
+1. Create a release PR: `release-plz release-pr --git-token <Github Token>`
+1. In the Pull Request:
+   1. Check that the new versions automatically determined by `release-plz` make sense
+      1. In the PR description, if there are API-breaking changes detected for a crate, make sure that that crate shows a major semver bump
+      1. If no API-breaking changes are detected, [conventional commits](https://www.conventionalcommits.org/) will be used to determine what type of version bump it should be. This means that `release-plz` may say there are no API-breaking changes detected, but there may still be a major version bump if the commit titles suggest there is a change that warrants it.
+      1. If the versions are not what you expect, you can manually override them by running `release-plz set-version <new semver version>`. This will update the package versions and the changelogs, but the PR description may need manual editing.
+1. Checkout the generated release branch locally in order to:
+   1. Update all docs to reflect new versions
+   1. Update all `cargo-make` files to use the new versions (ex. for `wdk-build` in [rust-driver-makefile.toml](./crates/wdk-build/rust-driver-makefile.toml))
+   1. Update all the [example drivers](./examples/) and [workspace-level tests](./tests/) to use new versions. These are not part of the same `cargo-workspace` as the rest of the crates, so they need to be updated manually.
+   1. Check that the release notes are correct and edit as needed
+1. Do a last sanity check of all of the [example drivers](./examples/) (i.e. install and verify that all logs are as expected)
+1. Run `release-plz release --dry-run` to check that the release will be successful
+1. Merge the release Pull Request
+1. Run `release-plz release`
+   1. This will release the crates to crates.io and create draft releases on Github
+1. Publish all the Github releases