feat(registry-scanner): List GCR as supported registry type

[patrickeasters]

What this PR does / why we need it:

To match the docs update, this updates the Helm chart to list GCR as an officially supported registry type.

Checklist

• Title of the PR starts with type and scope, (e.g. feat(agent,node-analyzer,sysdig-deploy):)
• Chart Version bumped for the respective charts
• Variables are documented in the README.md (or README.tpl in some charts)
• Check GithubAction checks (like lint) to avoid merge-check stoppers
• All test files are added in the tests folder of their respective chart and have a "_test" suffix

[mavimo]

@patrickeasters 👋

You need to run the make docs command to update the README file after the version bump

[patrickeasters]

@patrickeasters 👋

You need to run the make docs command to update the README file after the version bump

Thanks! Fixed. I had a wrong version of chart-doc-gen installed that was making a mess of things when I did that earlier.