docs: Remove node groups from nav

[Zvikan]

What does this PR do?

• removes node groups from github pages nav following chore: Remove examples that are related to EKS Blueprints cluster modules #1104
  🛑 Please open an issue first to discuss any significant work and flesh out details/direction - we would hate for your time to be wasted.
  Consult the CONTRIBUTING guide for submitting pull-requests.

Motivation

• Resolves Documentation Link to Node Groups is broken #1139

More

• Yes, I have tested the PR using my local account setup (Provide any test evidence report under Additional Notes)
• Yes, I have added a new example under examples to support my PR
• Yes, I have created another PR for add-ons under add-ons repo (if applicable)
• Yes, I have updated the docs for this feature
• Yes, I ran pre-commit run -a with this PR

Note: Not all the PRs require a new example and/or doc page. In general:

• Use an existing example when possible to demonstrate a new addons usage
• A new docs page under docs/add-ons/* is required for new a new addon

For Moderators

• E2E Test successfully complete before merge?

Additional Notes