fix file path

[louisachu]

connector is not reading the path correctly without the index.md with the directory

Description

Fix the buildNavigation to add the index.md when it's only pointing to a directory without any md files.

Related Issue

https://jira.corp.adobe.com/browse/DEVSITE-1629

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• [x ] My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.