docs: fix missing parentheses in about.tsx example file (#3143)

Co-authored-by: Marvin Hagemeister <hello@marvinh.dev>

Author: guzman109

docs/canary/getting-started/index.md

@@ -58,7 +58,7 @@ export default define.page(() => {
       <p>This is the about page.</p>
     </main>
   );
-}
+});
 ```
 
 If we navigate to `/about` in the browser we'll see our newly created page.
@@ -110,7 +110,7 @@ export default define.page(() => {
       <Countdown />
     </main>
   );
-}
+});
 ```
 
 Now, we can see our countdown in action: