docs: mic: convert docs to ReST and rename to *.rst

Convert Intel Many Integrated Core architecture docs to ReST.

The conversion is trivial: just add title and literal block
markups, and adjust some identation.

At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>