Document how releases are done in the readme

Also create separate release PR and release workflows

.github/workflows/release.yml

@@ -1,4 +1,7 @@
 # https://release-plz.ieni.dev/docs/github/quickstart#example-release-pr-and-release
+# We use a separate workflow to release vs create a release PR -- this is because we (currently) only want to
+# create a release PR after the `Feature Powerset` workflow completes, but we want to publish any merged release
+# commits once they're merged to `main`.
 
 name: Release
 
@@ -7,20 +10,14 @@ permissions:
   contents: write
 
 on:
-  workflow_run:
-    # Releases are performed after the `Feature Powerset` workflow completes successfully. Currently, `Feature Powerset`
-    # runs once a week, so releases will also be performed once a week.
-    workflows: [ Feature Powerset ]
-    types:
-      - completed
+  push:
     branches:
       - main
 
 jobs:
   release:
     name: Release
     runs-on: ubuntu-latest
-    if: ${{ github.event.workflow_run.conclusion == 'success' }}
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4
@@ -30,11 +27,8 @@ jobs:
         uses: dtolnay/rust-toolchain@stable
       - name: Run release-plz
         uses: MarcoIeni/[email protected]
+        with:
+          command: release
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}
-  on-powerset-failure:
-    runs-on: ubuntu-latest
-    if: ${{ github.event.workflow_run.conclusion == 'failure' }}
-    steps:
-      - run: echo 'The `Feature Powerset` workflow failed, skipping release.'

.github/workflows/release_pr.yml

@@ -0,0 +1,40 @@
+# https://release-plz.ieni.dev/docs/github/quickstart#example-release-pr-and-release
+
+name: Release PR
+
+permissions:
+  pull-requests: write
+  contents: write
+
+on:
+  workflow_run:
+    # Release PRs are created after the `Feature Powerset` workflow completes successfully. Currently,
+    # `Feature Powerset` runs once a week, so release PRs will also be created once a week.
+    workflows: [ Feature Powerset ]
+    types:
+      - completed
+
+jobs:
+  release-pr:
+    name: Release PR
+    runs-on: ubuntu-latest
+    if: ${{ github.event.workflow_run.conclusion == 'success' }}
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: Install Rust toolchain
+        uses: dtolnay/rust-toolchain@stable
+      - name: Run release-plz
+        uses: MarcoIeni/[email protected]
+        with:
+          command: release-pr
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}
+  on-powerset-failure:
+    runs-on: ubuntu-latest
+    if: ${{ github.event.workflow_run.conclusion == 'failure' }}
+    steps:
+      - run: echo 'The `Feature Powerset` workflow failed, skipping release.'

README.md

@@ -178,3 +178,23 @@ open target/debug/coverage/index.html
 # Delete the *.profraw files generated by the coverage tooling
 rm coverage/$USER-*.profraw
 ```
+
+# Releases
+
+Releases are created and published to crates.io using [release-plz](https://github.com/MarcoIeni/release-plz) via
+our [Release PR][ReleasePRLink] and [Release][ReleaseLink] workflows. The [Release PR][ReleasePRLink] workflow runs when
+the [Feature Powerset][FeaturePowersetLink] workflow completes successfully. The [Feature Powerset][FeaturePowersetLink]
+workflow is scheduled to run once a week, so release PR will also be created once a week. If an unscheduled release
+needs to be created, the [Feature Powerset][FeaturePowersetLink] workflow can also be triggered manually, and
+the [Release PR][ReleasePRLink] workflow will run once the [Feature Powerset][FeaturePowersetLink] workflow completes.
+Once a release PR is merged to `main`, the [Release][ReleaseLink] workflow will publish the release.
+
+Note that we use the default `GITHUB_TOKEN` to create the release PRs. This means that the PR checks [will not
+run automatically](https://docs.github.com/en/actions/security-guides/automatic-token-authentication#using-the-github_token-in-a-workflow).
+To get the checks to run, simply close and re-open the release PR.
+
+[ReleaseLink]: https://github.com/roadster-rs/roadster/blob/main/.github/workflows/release.yml
+
+[ReleasePRLink]: https://github.com/roadster-rs/roadster/blob/main/.github/workflows/release_pr.yml
+
+[FeaturePowersetLink]: https://github.com/roadster-rs/roadster/blob/main/.github/workflows/feature_powerset.yml