13.C Programmatic headings visual

**Description**

Modify [13.C Identify Content](https://ictbaseline.access-board.gov/web-baselines/13Structure/#identify-content-2) to apply only to Programmatically determined headings (`<h1>` to `<h6>` or ARIA `role="heading"`) that are visible on the page 


**Which Baseline**
To help us address your issue more effectively, please identify which Baseline has the issue:

- All