Updated doc to use tlsManagerSettings

As per Snoyberg's own answer on http://stackoverflow.com/questions/25829613/why-is-my-yesod-app-throwing-a-tlsnotsupported-exception-when-i-try-to-log-in.
I don't know why this was not corrected - perhaps there is a good reason :)
Merge pull request #119 from adamschoenemann/master

Updated doc to use tlsManagerSettings