(New) draft Preface for Getting Started Guide

I have written a (new) draft Preface for the Getting Started Guide. It
includes a bit of new material (most of which was previously found on
the back cover of the printed version of the book) and a few sections
extracted from Chapter 1 and Appendix B, which I think go better right
up front in the book. Comments and editing welcome.

http://www.odfauthors.org/libreoffice/english/getting-started/draft-lo3.4/gs3.4-preface/view

If no one objects, I will make this part of the book and revise
Chapter 1 and Appendix B to remove the material used in the Preface.

--Jean