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

There are only two files within Documentation/aoe dir that are
documentation. The remaining ones are examples and shell
scripts.

Convert the two AoE files to ReST format, and add the others
as literal, as they're part of the documentation.

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>