'addTodo' and 'setVisibilityFilter' actions are unused in index.html example

[dualcyclone]

I was just annotating a print out of the code to remind myself of some of the concepts learned in the video tutorials, and found the following issues:

• addTodo action is unused: should replace the dispatch action in the AddTodo component
• setVisibilityFilter action is unused: should be used by the dispatch action in the mapDispatchToLinkProps method