docs(testing-guide): fix tiny typo (#2381)

Author: petebacondarwin

public/docs/ts/latest/guide/testing.jade

@@ -917,7 +917,7 @@ a#component-with-inputs-outputs
     at low cost and without resorting to much slower and more complicated end-to-end tests.
 
 :marked
-  The second test verifies click behavior. Clicking the hero should rais a `selected` event that the
+  The second test verifies click behavior. Clicking the hero should raise a `selected` event that the
   host component (`DashboardComponent` presumably) can hear:
 +makeExample('testing/ts/app/dashboard/dashboard-hero.component.spec.ts', 'click-test', 'app/dashboard/dashboard-hero.component.spec.ts (click test)')(format='.')
 :marked