Authentication and Authorization chapter

I just created PR #309 "Authentication and Authorization chapter in CORE
doc created via input from VIWI. TRANSPORT doc updated to match VSS 2.0
modelling."

You can view the rendered files by copying the following links into a
browser:
https://raw.githack.com/UlfBj/automotive/gh-pages/spec/Gen2_Core.html

<https://github.com/UlfBj/automotive/blob/gh-pages/spec/Gen2_Core.html>
https://raw.githack.com/UlfBj/automotive/gh-pages/spec/Gen2_Transport.html

Feedback can be provided on the related issue
https://github.com/w3c/automotive/issues/308

If it is not entirely disapproved I propose we merge it into the gh-pages
branch, and refine it from there.

BR
Ulf