docs(tutorial): Fix spelling error in ToH tutorial pt4

public/docs/ts/latest/tutorial/toh-pt4.jade

@@ -306,7 +306,7 @@ code-example(format="." language="html").
 .l-sub-section
   :marked
     The [ES2015 arrow function](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions)
-    in the callback is more succint than the equivalent function expression and gracefully handles *this*.
+    in the callback is more succinct than the equivalent function expression and gracefully handles *this*.
 :marked
   Our callback sets the component's `heroes` property to the array of heroes returned by the service. That's all there is to it!