Draft: Link Helm chart documentation to reference architectures

Why is this change being made?

Closes gitlab-org/gitlab#351145 (moved)

Our reference architectures for cloud native deployment recommend against deploying all GitLab components with Kubernetes, but the Helm chart documentation does not make any such assertion nor link to the reference architectures for guidance. This is causing confusion for customers, and a sub-optimal experience for production deployments.

This merge request adds clarity in the Helm chart documentation that reference architectures should be consulted for production instances, and that customers should follow that guidance over the technical capabilities listed in the Helm chart documentation.

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