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

Converts ARM the text files to ReST, preparing them to be an
architecture book.

The conversion is actually:
  - add blank lines and identation in order to identify paragraphs;
  - fix tables markups;
  - add some lists markups;
  - mark literal blocks;
  - adjust title markups.

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>
Reviewed-by Corentin Labbe <clabbe.montjoie@gmail.com> # For sun4i-ss
diff --git a/Documentation/index.rst b/Documentation/index.rst
index 216dc0e..c6934d9 100644
--- a/Documentation/index.rst
+++ b/Documentation/index.rst
@@ -1,3 +1,4 @@
+
 .. The Linux Kernel documentation master file, created by
    sphinx-quickstart on Fri Feb 12 13:51:46 2016.
    You can adapt this file completely to your liking, but it should at least