app spec - add requirement of autofocus new todo input on page load

#1029

app-spec.md

@@ -86,7 +86,7 @@ When there are no todos, `#main` and `#footer` should be hidden.
 
 ### New todo
 
-New todos are entered in the input at the top of the app. Pressing Enter creates the todo, appends it to the todo list and clears the input. Make sure to `.trim()` the input and then check that it's not empty before creating a new todo.
+New todos are entered in the input at the top of the app. The input element should be focused when the page is loaded preferably using the `autofocus` input attribute. Pressing Enter creates the todo, appends it to the todo list and clears the input. Make sure to `.trim()` the input and then check that it's not empty before creating a new todo.
 
 ### Mark all as complete