add release process description (#329)

* add release process description

* Update RELEASE.md

Co-authored-by: Sherif Akoush <sherif.akoush@gmail.com>

* Update RELEASE.md

Co-authored-by: Sherif Akoush <sherif.akoush@gmail.com>

* Update RELEASE.md

Co-authored-by: Sherif Akoush <sherif.akoush@gmail.com>

Co-authored-by: Sherif Akoush <sherif.akoush@gmail.com>

RELEASE.md

@@ -0,0 +1,79 @@
+# Release Process
+
+This document summarize the release process for Seldon Core V2.
+This document is meant mainly at the maintainers.
+
+
+
+> :warning: **NOTE:** This is work in progress. This is a very initial version of the release process. The process may change. Please, always check this document before conducting a release and verify if everything goes as expected.
+
+
+
+## Process Summary
+
+1. Cut branch for release, e.g. `release-0.1`
+2. Run "Draft New Release" workflow (e.g. choose `release-0.1` branch and `v0.1.0-rc1` version)
+3. Run "Build docker images" workflow (e.g. choose `release-0.1` branch and `0.1.0-rc1` tag)
+4. Verify correctness or created artifacts and images (not yet automated!)
+5. Publish the release.
+
+
+## Process discussion
+
+The development process follows a standard GitHub workflow.
+
+![Development Graph](.images/release-1.png)
+
+The main development is happening in `master` branch.
+This is where new features land through Pull Requests.
+When all features for new release are merged, for example `v0.1.0`, we cut a branch for `release-0.1`.
+
+The `release-0.1` branch will be base for `v0.1.0` release as well as the release candidates, e.g. `v0.1.0-rcX` and successive patch releases `v0.1.X`.
+We use GitHub Actions to prepare the release, build images and run all necessary testing.
+
+If the release draft needs to be updated before the release is published, the new commits should be merged into the `release-0.1` branch and relevant workflows re-triggered as required.
+
+![Draft Update Graph](.images/release-2.png)
+
+
+### Draft New Release Action
+
+The [Draft New Release](./.github/workflows/draft-release.yml) workflow is the first one to run.
+It must be triggered manually using the [Actions](https://github.com/SeldonIO/seldon-core-v2/actions/workflows/draft-release.yml) interface in GitHub UI.
+
+When triggering the workflow, you must:
+- select the release branch (here `release-0.1`)
+- specify the release `version` (here `v0.1.0-rc1`).
+
+![Triggering Draft Workflow](.images/release-4.png)
+
+This workflow cannot run on `master` branch.
+It will also validate provided `version` against SemVer regex.
+
+It will create a few commits with:
+- updated helm charts
+- updated k8s yaml manifests
+- updated changelog
+
+![Created Commits](.images/release-3.png)
+
+Once the workflow finishes, you will find a new release draft waiting to be published.
+
+![Draft Release](.images/release-5.png)
+
+> :warning: **NOTE:** Before publishing the release run the images build workflow and necessary tests (not yet automated)!
+
+
+### Build docker images Action
+
+The [Build docker images](./.github/workflows/images.yml) workflow is the second one to run.
+
+It must be triggered manually using the [Actions](https://github.com/SeldonIO/seldon-core-v2/actions/workflows/draft-release.yml) interface in GitHub UI.
+
+When triggering the workflow, you must:
+- select the release branch (here `release-0.1`)
+- specify the release `version` (here `0.1.0-rc1` - note lack of `v` prefix!).
+
+![Triggering Build images](.images/release-6.png)
+
+This workflow will then run unit tests and build a series of Docker images that will be automatically pushed to [DockerHub](https://hub.docker.com/).