[docs] design shuffle (#2951)

This PR incorporates design tweaks from #2922 without the home page or
content changes.

These are:
- Replacing all `hello@tldraw.com` with `sales@tldraw.com`
- Fix mailto links.
- Showing the first item in a section on direct routes to the section
- Splitting the article page for human-written content from article page
for generated content
- Splitting the layout for the landing page from the rest of the site
(temporarily identical to the regular content)
- Removing headings from left sidebar
- Restoring headings in right sidebar for human-written pages with > 1
heading link
- Styling block quote
- Adjusting section link appearance / layout in header / menu
- Changing the order of search results to preference docs over examples
- Updating copy on events
- Removing copy on user interface menus
- Adding hero as prop to all articles
- Updated icon
- Fixing a few broken links
- Replaces the sandpack code blocks with hljs code blocks, except in
examples.

### Change Type

- [x] `documentation` — Changes to the documentation only[^2]

apps/docs/components/CategoryDocsPage.tsx

@@ -23,10 +23,8 @@ export async function CategoryDocsPage({ category }: { category: Category }) {
 				{articles.length > 0 && (
 					<ul>
 						{articles.map((article) => (
-							<li>
-								<Link key={article.id} href={`/${section.id}/${category.id}/${article.id}`}>
-									{article.title}
-								</Link>
+							<li key={article.id}>
+								<Link href={`/${section.id}/${category.id}/${article.id}`}>{article.title}</Link>
 							</li>
 						))}
 					</ul>