[Doc] Update horizontal navigation reference

[emmanuel-ferdman]

Problem

Commit e0eb015 moved the location of the horizontal navigation source file without updating the sources.

Solution

PR updates the sources with changes.

How To Test

Describe the steps required to test the changes

Additional Checks

• The PR targets master for a bugfix, or next for a feature
• The PR includes unit tests (if not possible, describe why)
• The PR includes one or several stories (if not possible, describe why)
• The documentation is up to date

Also, please make sure to read the contributing guidelines.

[djhi]

Thanks!