fix: Add missing description to frontmatter for EKS Hybrid Nodes module

[raykrueger]

EKS Hybrid Nodes module preview was showing ::required-time because the description frontmatter is missing.

What this PR does / why we need it:

Which issue(s) this PR fixes:

Fixes #

Quality checks

• [ x] My content adheres to the style guidelines
• [ x] I ran make test module="<module>" it was successful (see https://github.com/aws-samples/eks-workshop-v2/blob/main/docs/automated_tests.md)
• [x ] The PR has meaningful title and description of the changes that will be included in the workshop release notes

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