fix(toh-pt3.jade): Typo 'ned' => 'need' (#3486)

Author: octo47

public/docs/ts/latest/tutorial/toh-pt3.jade

@@ -7,7 +7,7 @@ include ../_util-fns
   Soon there will be new requirements and capabilities.
   You can't keep piling features on top of features in one component; that's not maintainable.
 
-  You'll ned to break it up into sub-components, each focused on a specific task or workflow.
+  You'll need to break it up into sub-components, each focused on a specific task or workflow.
   Eventually, the `AppComponent` could become a simple shell that hosts those sub-components.
 
   In this page, you'll take the first step in that direction by carving out the hero details into a separate, reusable component.