chore: update release template (#257)

Co-authored-by: Mattia Lavacca <[email protected]>

.github/ISSUE_TEMPLATE/---release.md

@@ -17,19 +17,35 @@ If the troubleshooting section does not contain the answer to the problem you en
 - [ ] Check the `CHANGELOG.md` and update it with the new version number. Make sure the log is up to date.
 - [ ] Ensure that all generators have run properly (e.g. `make generate manifests`) so that updates to things like CRDs are handled for the release, double check that all manifests from `config/samples/` still work as intended.
 - [ ] Ensure GitHub PAT is still valid (see [GitHub PAT](#github-pat) below).
-- [ ] From [GitHub release action][release-action], start a new workflow run with the `release` input set to the release tag (e.g. `v0.1.0`).
+- [ ] If the new release is a new major/minor then branch off of `main` and create a branch `release/N.M.x`, e.g. 
+- [ ] From [GitHub release action][release-action], start a new workflow run:
+  - Set the `Use workflow from` to the release branch: e.g. `release/1.2.x`
+  - Set the `release` input set to the target version (e.g. `v1.2.0`).
 - [ ] Wait for the workflow to complete.
-- [ ] The CI should create a PR in the [Gateway Operator][kgo-prs] repo that syncs the release branch to the `main` branch. Merge it.
+- [ ] The CI should create a PR in the [Gateway Operator][kgo-prs] repo that syncs the release branch to the base branch (either `main` or `release/N.M.x`, e.g. `release/1.2.x`) branch. Merge it.
 - [ ] After the PR is merged, a new release should be created automatically. Check the [releases][releases] page. The release has to be marked manually as `latest` if this is the case.
 - [ ] Update the official documentation at [github.com/Kong/docs.konghq.com][docs_repo]
-  - [ ] Run post processing script for `docs/api-reference.md`, providing a tagged version of CRD reference from docs repo as an argument, e.g. `app/_src/gateway-operator/reference/custom-resources/1.2.x.md`. This will add the necessary skaffolding so that the reference is rendered correctly on docs.konghq.com.
-    Example: `${GATEWAY_OPERATOR_REPO}/scripts/apidocs-gen/post-process-for-konghq.sh ~/docs.konghq.com/app/_src/gateway-operator/reference/custom-resources/1.2.x.md`
-  - NOTE: [CLI configuration options docs][cli_ref_docs] should be updated when releasing KGO EE as that's the source of trutgh for those.
+  - [ ] Run post processing script for `docs/api-reference.md`, providing a tagged version of CRD reference from docs repo as an argument, e.g. `app/_src/gateway-operator/reference/custom-resources/1.2.x.md`.
+    This will add the necessary skaffolding so that the reference is rendered correctly on docs.konghq.com.
+
+    Example:
+    ```
+    ${GATEWAY_OPERATOR_REPO}/scripts/apidocs-gen/post-process-for-konghq.sh ~/docs.konghq.com/app/_src/gateway-operator/reference/custom-resources/1.2.x.md
+    ```
+
+  - NOTE: [CLI configuration options docs][cli_ref_docs] should be updated when releasing KGO EE as that's the source of truth for those.
     The reason for this is that KGO EE configuration flags are a superset of OSS flags.
+
 - [ ] Proceed to release KGO EE as it relies on OSS releases.
 
+**Only for major and minor releases**:
+
+- [ ] When the release tag is created add a test case in [upgrade E2E test][helm_upgrade_test] with just published tag so that an upgrade path from previous major/minor version is tested.
+  - [ ] When the release contains breaking changes which precludes an automated upgrade make sure to add a comment to this test for future readers.
+
 [docs_repo]: https://github.com/Kong/docs.konghq.com/
 [cli_ref_docs]: https://docs.konghq.com/gateway-operator/latest/reference/cli-arguments/
+[helm_upgrade_test]: https://github.com/Kong/gateway-operator/blob/9f33d27ab875b91e50d7e750b45a293c1395da2d/test/e2e/test_upgrade.go
 
 ## Verify default hardcoded versions
 
@@ -43,16 +59,13 @@ The package [internal/consts][consts-pkg] contains a list of default versions fo
 
 **Next expiration date**: 2024-10-02
 
-The release workflow uses @team-k8s-bot's GitHub PAT to create a GitHub release and PRs related to it (in [KGO docs][operator-docs],
-[OperatorHub][community-operators], etc.). It's named `Kong Gateway operator release pipeline` and is stored in `PAT_GITHUB`
+The release workflow uses @team-k8s-bot's GitHub PAT to create a GitHub release and PRs related to it.
+It's named `Kong Gateway operator release pipeline` and is stored in `PAT_GITHUB`
 GitHub repository secret to give workflows access to it. It's always generated with 1-year expiration date.
 
 If you find it's expired, make sure to generate a new one and update the `PAT_GITHUB` secret as well as its 1Pass item
 `Github team k8s bot - PAT - Kong Gateway operator release token` for redundancy.
 
-[operator-docs]: https://github.com/Kong/gateway-operator-docs
-[community-operators]: https://github.com/Kong/k8s-operatorhub-community-operators
-
 ## Troubleshooting
 
 ### The release needs to be started again with the same tag
@@ -69,13 +82,11 @@ Otherwise, if the above conditions are not meet, the release cannot be restarted
 
 Steps:
 
-1. Delete the `release/v<version>` branch.
-2. Delete the PR created by a release workflow.
-3. Update the repository with the correct changes.
-4. Start a new release workflow run.
+1. Delete the PR created by a release workflow.
+1. Update the repository with the correct changes.
+1. Start a new release workflow run.
 
 [releases]: https://github.com/Kong/gateway-operator/releases
 [release-action]: https://github.com/Kong/gateway-operator/actions/workflows/release.yaml
 [consts-pkg]: https://github.com/Kong/gateway-operator/blob/main/internal/consts/consts.go
-[operator-hub-community]: https://github.com/k8s-operatorhub/community-operators
 [kgo-prs]: https://github.com/Kong/gateway-operator/pulls