Remove misleading example

[erikwright]

While the example is interesting in that it shows an example of advanced pattern matching, it is problematic in that the pattern used is not of a valid type for the rest of the code.

As it is not really relevant to the issue at hand, and given that it's a relatively advanced example not likely to be relevant to someone first learning the language, I suggest simply removing it. A separate section on advanced pattern matching could potentially cover it.

Fixes #34

[AdrianRaFo]

I suggest to change it to:

// A list that starts with `2`	
     case 2 :: xs => …