Heading anchor links are not displayed for headings h3-h6

Anchor links should be shown next to every heading in the content with size h2-h6.

Steps to reproduce:

1. Create a page with headings of different sizes h2-h6

2. Setup Viewport using default HC theme

3. Open the page in Viewport

Expected result:

An anchor link is displayed next to every heading in the content when hovering over it

Actual result:

Only h2 heading show anchor links when hovered