correct typo

src/app/app.component.html

@@ -17,7 +17,7 @@
     <h2><a target="_blank" rel="noopener" href="https://blog.angular.io/">Angular blog</a></h2>
   </li>
   <li>
-    <h2><a routerLink="/errorpage">Error Langing Page</a></h2>
+    <h2><a routerLink="/errorpage">Error Landing Page</a></h2>
   </li>
 </ul>
 

src/app/error-landing-page/error-landing-page.component.html

-<h1>404</h1>>
-<h2>The page you were looking for was not found</h2> 
+<h1>404</h1>
+<h3>The page you were looking for was not found</h3>