Add release documentation for Pipeline

Add the release policy and list of releases for Pipeline.
This documented may be automated in future, it's maintained
manually for now.
Updated the release process accordingly.

Fixes: tektoncd#5399

Signed-off-by: Andrea Frittoli <[email protected]>

README.md

@@ -30,6 +30,7 @@ Tekton Pipelines are **Typed**:
 - [Installing Tekton Pipelines](docs/install.md)
 - Jump in with [the "Getting started" tutorial!](https://tekton.dev/docs/getting-started/tasks/)
 - Take a look at our [roadmap](roadmap.md)
+- Discover our [releases](releases.md)
 
 ### Required Kubernetes Version
 

releases.md

@@ -0,0 +1,100 @@
+# Tekton Pipeline Releases
+
+## Release Frequency
+
+Tekton Pipelines follows the Tekton community [release policy][release-policy]
+as follows:
+
+- Versions are numbered according to semantic versioning: `vX.Y.Z`
+- A new release is produced on a monthly basis
+- Four releases a year are chosen for [long term support (LTS)](https://github.com/tektoncd/community/blob/main/releases.md#support-policy).
+ All remaining releases are supported for approximately 1 month (until the next
+ release is produced)
+ - LTS releases take place in January, April, July and October every year
+ - The first Tekton Pipelines LTS release will be **v0.41.0** in October 2022
+ - Releases happen towards the middle of the month, between the 13th and the
+ 20th, depending on week-ends and readyness
+
+Tekton Pipelines produces nightly builds, publicly available on
+`gcr.io/tekton-nightly`. 
+
+### Transition Process
+
+Before release v0.41 Tekton Pipelines has worked on the basis of an undocumented
+support period of four months, which will be maintained for the releases between
+v0.37 and v0.40.
+
+## Release Process
+
+Tekton Pipeline releases are made of YAML manifests and container images.
+Manifests are published to cloud object-storage as well as
+[GitHub][tekton-pipeline-releases]. Container images are signed by
+[Sigstore][sigstore] via [Tekton Chains][tekton-chains]; signatures can be
+verified through the [public key][chains-public-key] hosted by the Tekton Chains
+project.
+
+Further documentation available:
+
+- The Tekton Pipeline [release process][tekton-releases-docs]
+- [Installing Tekton][tekton-installation]
+- Standard for [release notes][release-notes-standards]
+
+## Releases
+
+### v0.40
+
+- **Latest Release**: [v0.40.1][v0-40-1] (2022-09-27)
+- **Initial Release**: [v0.40.0][v0-40-0] (2022-09-16)
+- **End of Life**: 2023-01-15
+- **Patch Releases**: [v0.40.0][v0-40-0], [v0.40.1][v0-40-1]
+
+### v0.39
+
+- **Latest Release**: [v0.39.0][v0-39-0] (2022-08-18)
+- **Initial Release**: [v0.39.0][v0-39-0] (2022-08-18)
+- **End of Life**: 2022-12-17
+- **Patch Releases**: [v0.39.0][v0-39-0]
+
+### v0.38
+
+- **Latest Release**: [v0.38.4][v0-38-4] (2022-09-14)
+- **Initial Release**: [v0.38.0][v0-38-0] (2022-07-25)
+- **End of Life**: 2022-11-24
+- **Patch Releases**: [v0.38.0][v0-38-0], [v0.38.1][v0-38-1], [v0.38.2][v0-38-2], [v0.38.3][v0-38-3], [v0.38.4][v0-38-4]
+
+### v0.37
+
+- **Latest Release**: [v0.37.5][v0-37-5] (2022-09-25)
+- **Initial Release**: [v0.37.0][v0-37-0] (2022-06-21)
+- **End of Life**: 2022-10-20
+- **Patch Releases**: [v0.37.0][v0-37-0], [v0.37.1][v0-37-1], [v0.37.2][v0-37-2], [v0.37.3][v0-37-3], [v0.37.4][v0-37-4]，[v0.37.5][v0-37-5]
+
+## End of Life Releases
+
+Older releases are EOL and available on [GitHub][tekton-pipeline-releases].
+
+
+[release-policy]: https://github.com/tektoncd/community/blob/main/releases.md
+[sigstore]: https://sigstore.dev
+[tekton-chains]: https://github.com/tektoncd/chains
+[tekton-pipeline-releases]: https://github.com/tektoncd/pipeline/releases
+[chains-public-key]: https://github.com/tektoncd/chains/blob/main/tekton.pub
+[tekton-releases-docs]: tekton
+[tekton-installation]: docs/install.md
+[release-notes-standards]:
+ https://github.com/tektoncd/community/blob/main/standards.md#release-notes
+
+[v0-40-1]: https://github.com/tektoncd/pipeline/releases/tag/v0.40.1
+[v0-40-0]: https://github.com/tektoncd/pipeline/releases/tag/v0.40.0
+[v0-39-0]: https://github.com/tektoncd/pipeline/releases/tag/v0.39.0
+[v0-38-4]: https://github.com/tektoncd/pipeline/releases/tag/v0.38.4
+[v0-38-3]: https://github.com/tektoncd/pipeline/releases/tag/v0.38.3
+[v0-38-2]: https://github.com/tektoncd/pipeline/releases/tag/v0.38.2
+[v0-38-1]: https://github.com/tektoncd/pipeline/releases/tag/v0.38.1
+[v0-38-0]: https://github.com/tektoncd/pipeline/releases/tag/v0.38.0
+[v0-37-5]: https://github.com/tektoncd/pipeline/releases/tag/v0.37.5
+[v0-37-4]: https://github.com/tektoncd/pipeline/releases/tag/v0.37.4
+[v0-37-3]: https://github.com/tektoncd/pipeline/releases/tag/v0.37.3
+[v0-37-2]: https://github.com/tektoncd/pipeline/releases/tag/v0.37.2
+[v0-37-1]: https://github.com/tektoncd/pipeline/releases/tag/v0.37.1
+[v0-37-0]: https://github.com/tektoncd/pipeline/releases/tag/v0.37.0

tekton/release-cheat-sheet.md

@@ -144,7 +144,9 @@ the pipelines repo, a terminal window and a text editor.
  (This can be done on the Github UI.)
  Make sure to fetch the commit specified in `TEKTON_RELEASE_GIT_SHA` to create the released branch.
 
-1. Edit `README.md` on `main` branch, add entry to docs table with latest release links.
+1. Edit `README.md` on `main` branch, add entry to docs table with latest release links. 
+
+1. Edit `releases.md` on the `main` branch, add an entry for the release.
 
 1. Push & make PR for updated `README.md`