Fixes table of contents navigation active link

[drolsen]

Description

Since making updates to the SgNavigation; how we gathered and located active link's index has changed. I've updated the code to be a bit more agnostic at how it gets an actual index now of links, vs trying to get a pointer to markup.

Motivation and Context

Fixes active or rather current link state. Without this fix, all pages you visit will always list the first link in the navigation as active page.

How Has This Been Tested?

While running a dev build, test the navigation links by clicking a few pages and confirm the active state follows you from page to page now.

Make sure:

• dev build
• full build
• production build

All are working still.
Thanks!

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:

• 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.