docs: Commit initial files from sphinx-quickstart

Commit the initial Sphinx conf.py and skeleton index.rst as
generated with sphinx-quickstart. We'll update these to
add QEMU-specific tweaks in subsequent commits.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Aleksandar Markovic <amarkovic@wavecomp.com>
Acked-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20190305172139.32662-4-peter.maydell@linaro.org
Message-id: 20190228145624.24885-4-peter.maydell@linaro.org