Doc

Created by: timsaxe

This commit sets up the documentation framework: rtl/../data/file.csv for files that define registers docs/Makefile copies csv into a mirror directory (there is probably a better make way, but I haven;t taken the time to find it) docs/Makefile runs util/ioscript.py to convert the csv files into auto-doc/.md docs/Makefile runs Sphinx to combine doc-src/, auto-doc/* into the document tree which can be found in _build/html

csv files and ioscript were modified to put module description before the register descriptions

overview.md was updated to include more information, especially about software validation