Minor comment fixes

[CormacBracken]

plugin.php, line 196

// TODO be sure to change 'widget-name' to the name of *your* plugin

This TODO is no longer needed since the code takes the text domain from the slug.

plugin.php, line 166

} // end widget

should be

} // end update

[tommcfarlin]

Shoot me a pull request, and I'll be happy to merge it!