[Accessibility] No H1 heading is defined in the 'Graph Explorer' page.

[ElinorW]

Test Environment:
OS Build: Version 22H2(OS Build 25136.1000) 
Browser: Version 104.0.1278.2 (Official build) dev (64-bit)
URL: Graph Explorer | Try Microsoft Graph APIs - Microsoft Graph
Tool- Accessibility insight for web
Screen reader: Narrator

Repro Steps:

1. Open above URL in Edge dev browser.
2. Turn on Narrator then scan mode using Caps+ Space key.
3. Navigate to headings on the page by pressing the 'h' in scan mode and also check with Accessibility insight tool.
4. Observe the issue here.

Actual Result:
No H1 heading is defined in the 'Graph Explorer' page.

Expected Result:
'Graph Explorer' text on the page should be defined under H1 heading tag programmatically.

User Impact:
Screen reader users will be confused with the structure of page if no H1 heading is defined programmatically on the page.

MAS Reference:
Info and Relationships - Liquid (microsoft.com)

Additional context
Issue: https://office.visualstudio.com/OC/_workitems/edit/6195406