Data.List documentation improvements

[Donald Bruce Stewart]

ndmitchell:
> Hi
> 
> >The deadline is Wednesday, December 6th.
> 
> That's incredibly soon, two days is just not enough time to do
> anything! I recommend a minimum deadline of a week for anything, some
> people may only catch up with their Haskell mail a couple of times a
> week.
> 
> As for your patch, I think its great, and its exactly the type of
> thing that should be in the libraries documentation for pretty much
> everything. My only suggestion would be to include the "corner" cases:
> 
> take 3 [1] = [1]
> drop 3 [1] = []
> 
> (ditto splitAt)
> 
> i.e. show that they produce a result, not an error.

In general, what do people think about adding examples by default to
anything we want in the libraries? Are people ok with this?

If so, we should add some guidelines for their constructoin:

I.e.
    * general cases
    * corner cases

and for some things, like the monad transformers:

    * entire programs

Seem reasonable? If so, i'll add some notes to the documentation
suggetions.

-- Don