WIP: Openshift Documentation: Update link in deprecation notice to proper guide on installing using helm charts.

What does this MR do?

This will update the link in the old OpenShift documentation so that it links to the proper guide to install using official helm charts. Currently this link gives a 404.

Related issues

None

Author's checklist

• Apply the correct labels and milestone
• Crosslink the document from the higher-level index
• Crosslink the document from other subject-related docs
• Feature moving tiers? Make sure the change is also reflected in features.yml
• Correctly apply the product badges and tiers
• Port the MR to EE (or backport from CE): always recommended, required when the ee-compat-check job fails

Review checklist

• Your team's review (required)
• PM's review (recommended, but not a blocker)
• Technical writer's review (required)
• Merge the EE-MR first, CE-MR afterwards