Update using-yaml-frontmatter.md (#39695)

Co-authored-by: Copilot <[email protected]>
Co-authored-by: Sharra-writes <[email protected]>

Author: 3 people

content/contributing/writing-for-github-docs/using-yaml-frontmatter.md

@@ -102,7 +102,7 @@ For more information, see [AUTOTITLE](/contributing/syntax-and-versioning-for-gi
 
 * Purpose: Set a human-friendly title for use in the rendered page's `<title>` tag and an `h1` element at the top of the page.
 * Type: `String`
-* Optional. If omitted, the page `<title>` will still be set, albeit with a generic value like `GitHub.com` or `GitHub Enterprise`.
+* **Required**.
 
 ### `shortTitle`