docs(toh): change data flow to data flows (#3467)

Author: kapunahelewong

public/docs/ts/latest/tutorial/toh-pt1.jade

@@ -120,7 +120,7 @@ code-example(language="sh" class="code-shell").
 :marked
   `[(ngModel)]` is the Angular syntax to bind the `hero.name` property
   to the textbox.
-  Data flow _in both directions_: from the property to the textbox;
+  Data flows _in both directions:_ from the property to the textbox,
   and from the textbox back to the property.
 
   Unfortunately, immediately after this change, the application breaks.