Update DEVELOPMENT_MAINTENANCE.md

Also updating Gluon and adding helmv3 package manager.

Steps for KPT update

1. Navigate to the upstream chart repo and folder (link) and find the tag that corresponds with the new chart version for this update
2. Checkout the renovate/ironbank branch
3. From the root of the repo run kpt pkg update chart@<tag> --strategy alpha-git-patch, where tag is found in step 1, checkout the chart/Kptfile ref for tag naming
4. Modify the version in Chart.yaml and append -bb.0 to the chart version from upstream. Update dependencies to latest BB gluon library version using: helm dependency update ./chart
5. Update CHANGELOG.md adding an entry for the new version and noting all changes (at minimum should include Updated <chart or dependency> to x.x.x).
6. Generate the README.md updates by following the guide in gluon.
7. Push up your changes, add upgrade notices if applicable, validate that CI passes. If there are any failures, follow the information in the pipeline to make the necessary updates. Add the debug label to the MR for more detailed information. Reach out to the CODEOWNERS if needed.
8. Perform the steps below for manual testing

Modifications made to upstream

List of changes per file to be aware of for how Big Bang differs from upstream

Manual Testing

NOTE: For these testing steps it is good to do them on both a clean install and an upgrade. For clean install, point <package> to your branch. For an upgrade do an install with <package> pointing to the latest tag, then perform a helm upgrade with <package> pointing to your branch.

• Add list of packages to install with
• Add Dev SSO values if needed
• Add an example overrides/<package>.yaml file
• Add testing steps for UI
• Add When in doubt with any testing or upgrade steps, reach out to the CODEOWNERS for assistance.