Type in classy-base-prelude; contreversial => controversial

Its only a 1 word change; the source diff makes that hard to see. If you look at the [rendered/rich diff](https://github.com/yesodweb/yesodweb.com-content/pull/115/files?short_path=509e076#diff-509e076504d463a6a0bde9ecb54ecc94) its more clear.