doc: introduce some minimalistic markdown without essential changes

The goal is to transform the standard documents

    README, INSTALL, SUPPORT, CONTRIBUTING, ...

from a pure text format into markdown format, but in such a way
that the documentation remains nicely formatted an easy readable
when viewed with an normal text editor.

To achieve this goal, we use a special form of 'minimalistic' markdown
which interferes as little as possible with the reading flow.

 * avoid [ATX headings][] and use [setext headings][] instead
   (works for `<h1>` and `<h2>` headings only).
 * avoid [inline links][] and use [reference links][] instead.
 * avoid [fenced code blocks][], use [indented-code-blocks][] instead.

The transformation will take place in several steps. This commit
introduces mostly changes the formatting and does not chang the
content significantly.

[ATX headings]:         https://github.github.com/gfm/#atx-headings
[setext headings]:      https://github.github.com/gfm/#setext-headings
[inline links]:         https://github.github.com/gfm/#inline-link
[reference links]:      https://github.github.com/gfm/#reference-link
[fenced code blocks]:   https://github.github.com/gfm/#fenced-code-blocks
[indented code blocks]: https://github.github.com/gfm/#indented-code-blocks

Reviewed-by: Tomas Mraz <[email protected]>
(Merged from openssl#10545)

ACKNOWLEDGEMENTS.md

@@ -1,2 +1,8 @@
-Please https://www.openssl.org/community/thanks.html for the current
-acknowledgements.
+Acknowlegements
+===============
+
+Please see our [Thanks!][] page for the current acknowledgements.
+
+
+[Thanks!]: https://www.openssl.org/community/thanks.html
+

AUTHORS.md

@@ -1,35 +1,46 @@
-# This is the list of OpenSSL authors for copyright purposes.
-#
-# This does not necessarily list everyone who has contributed code, since in
-# some cases, their employer may be the copyright holder.  To see the full list
-# of contributors, see the revision history in source control.
-OpenSSL Software Services, Inc.
-OpenSSL Software Foundation, Inc.
+Authors
+=======
 
-# Individuals
-Andy Polyakov
-Ben Laurie
-Ben Kaduk
-Bernd Edlinger
-Bodo Möller
-David Benjamin
-Emilia Käsper
-Eric Young
-Geoff Thorpe
-Holger Reif
-Kurt Roeckx
-Lutz Jänicke
-Mark J. Cox
-Matt Caswell
-Matthias St. Pierre
-Nils Larsch
-Paul Dale
-Paul C. Sutton
-Ralf S. Engelschall
-Rich Salz
-Richard Levitte
-Stephen Henson
-Steve Marquess
-Tim Hudson
-Ulf Möller
-Viktor Dukhovni
+This is the list of OpenSSL authors for copyright purposes.
+It does not necessarily list everyone who has contributed code,
+since in some cases, their employer may be the copyright holder.
+To see the full list of contributors, see the revision history in
+source control.
+
+
+Groups
+------
+
+ *  OpenSSL Software Services, Inc.
+ *  OpenSSL Software Foundation, Inc.
+
+
+Individuals
+-----------
+
+ *  Andy Polyakov
+ *  Ben Laurie
+ *  Ben Kaduk
+ *  Bernd Edlinger
+ *  Bodo Möller
+ *  David Benjamin
+ *  Emilia Käsper
+ *  Eric Young
+ *  Geoff Thorpe
+ *  Holger Reif
+ *  Kurt Roeckx
+ *  Lutz Jänicke
+ *  Mark J. Cox
+ *  Matt Caswell
+ *  Matthias St. Pierre
+ *  Nils Larsch
+ *  Paul Dale
+ *  Paul C. Sutton
+ *  Ralf S. Engelschall
+ *  Rich Salz
+ *  Richard Levitte
+ *  Stephen Henson
+ *  Steve Marquess
+ *  Tim Hudson
+ *  Ulf Möller
+ *  Viktor Dukhovni