Fix the tick_loop example documentation layout.

# Before  

(as can be seen [here](http://eventmachine.rubyforge.org/EventMachine/TickLoop.html))

![Before](https://api.monosnap.com/image/download?id=1MCTshDaqk3xG93sh3SuFGtLGtZVNW)

# After

![After](https://api.monosnap.com/image/download?id=LFDwaWzWX0tSk9d9MEYHCpP35ny2eN)