uart: Drop extensive protocol info (moved to wiki).

uart: Drop extensive protocol info (moved to wiki).

Move the full details of the protocol to the wiki, the docs in the PD
itself should only be a short description and/or a collection of notes
that could be useful for a user in a GUI (or CLI) to decide which
PD to select, which options to set how, what PDs to stack where, and so on.

The full protocol description (including photos, examples, ...) is here:

  http://sigrok.org/wiki/Protocol_decoder:Uart