Issue #572 - Set navigation grand parent

[johnwalicki]

Pull Request Template

Description

Please include a summary of the change and which issue is fixed. Please also include relevant motivation and context. List any dependencies that are required for this change.

Fixes #572
Related to Issue #564 and PR #571 , the new pages do not appear in the navigation. The fix is to add the appropriate grand_parent: directive tags to those updated pages:

• install_k3s_edge_cluster.md
• install_microk8s_edge_cluster.md
• install_ocp_edge_cluster.md

Type of change

• Bug fix (non-breaking change which fixes an issue)
• This change requires a documentation update

How Has This Been Tested?

Visit https://open-horizon.github.io/docs/installing/preparing_edge_cluster/ and its child pages after the PR has been merged.

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Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• I have checked my code and corrected any misspellings
• I have tagged the reviewers in a comment below incase my pull request is ready for a review
• I have signed the commit message to agree to Developer Certificate of Origin (DCO) (to certify that you wrote or otherwise have the right to submit your contribution to the project.) by adding "--signoff" to my git commit command.