Update options.plugins to be an array as expected, fix typo

I was creating a plugin for the first time and didn't realize plugins needed to be an array. Also, fixed a typo. The example link doesn't work, and I don't know what is supposed to be on that page... 

A few of your other example pages are broken:
http://listjs.com/examples/annotated-example
http://listjs.com/examples/menu