[5.0] Fix a few things for Pagination.

Some docBlocks lines has been improved. Some lines, now more readable.

@taylorotwell now, simplePaginate has been deleted. In my opinion, paginate method use the LengthAwarePaginator class. We will create simplePaginate again for Paginator class. So that, new Laravel version is provided for backward compatibility.
Please don't do this. Just remove the entire return statement, and don't return anything.