TODO item: Add info on USB printers

[Juris Kaminskis]

> Thank you for working on this.  The entire printing chapter really needs a
>> rewrite, and I've been meaning to write an outline for what a new printing
>> chapter should cover.  In the meantime, please look at
>> http://www.wonkity.com/~wblock/docs/html/lpdprinting.html and see if it
>> is adequate in the meantime.
>>
>
I am not sure I understand what should I do next from this. Can you let me
know how can I contribute further?