add increase header levels on support page
add increase header levels on support page

Summary:
from WAVE

> Headings facilitate page navigation for users of many assistive technologies. They also provide semantic and visual meaning and structure to the document. A first level heading (<h1>) should be present on nearly all pages. It should contain the most important heading on the page (generally the document title).

https://webaim.org/standards/wcag/checklist#sc1.3.1

In order to not skip header levels, also upgrade h3 to h2

Reviewed By: fanzeyi

Differential Revision: D30490581

fbshipit-source-id: 1c05da7bf082a7ad3b7939e6e5003d0c8583822e

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