add support for custom document and category titles (#43340)

* add support for custom document and category titles

* remove the s in the source file instead of the manifest

---------

Co-authored-by: Ron Rennick <ronald.rennick@automattic.com>

docs/user-experience/notices.md

@@ -1,5 +1,6 @@
 ---
 post_title: Notices
+menu_title: Notice guidelines
 ---
 
 ## Notices

tools/monorepo-utils/src/md-docs/lib/generate-frontmatter.ts

@@ -24,6 +24,7 @@ export const generatePostFrontMatter = (
 		'category_title',
 		'category_slug',
 		'content',
+		'menu_title',
 	];
 
 	const frontMatter = matter( fileContents, {

tools/monorepo-utils/src/md-docs/lib/generate-manifest.ts

@@ -55,6 +55,7 @@ async function processDirectory(
 			category.content = frontMatter.content;
 			category.category_slug = frontMatter.category_slug;
 			category.category_title = frontMatter.category_title;
+			category.menu_title = frontMatter.menu_title;
 		}
 		// derive the category title from the directory name, capitalize first letter of each word.
 		const categoryFolder = path.basename( subDirectory );