Refactor the huge README.md into the more structured mkdocs.

I also cleaned up the installation section and added links to various
competing redo implementations.

The new README.md is basically just link to the docs on
readthedocs.org, and a link to the mailing list.

These docs need a *lot* more work, but this is enough of an improvement
that I'll commit it anyway for now.

Documentation/Contributing.md

@@ -0,0 +1,57 @@
+# License
+
+My version of redo was written without ever seeing redo code by Bernstein or
+Grosskurth, so I own the entire copyright.  It's distributed under the GNU
+LGPL version 2.  You can find a copy of it in the file called LICENSE.
+
+minimal/do is in the public domain so that it's even easier
+to include inside your own projects for people who don't
+have a copy of redo.
+
+
+# How can I help?
+
+Nowadays, redo is good enough for real production use, and some people
+are using it for real work.  That said, it has
+not reached version 1.0 and there are surely still bugs.
+
+If you run into a problem, it's really helpful if you report it to the
+mailing list below (with or without subscribing first).  We really want to
+know if redo is acting weird for you.  Even if the problem turns out to be
+operator error, we can use that information to try to improve this
+documentation.
+
+Small feature additions are also welcome, but you might want to ask on the
+mailing list before you start working on it.  The code is still evolving and
+might not be the same by the time you submit your pull request.
+
+The best things you can do for redo are:
+
+- Convert your projects to using it.  Without users, no project is
+  successful.
+
+- Build new infrastructure around redo, especially things to make it easier
+  for people to get started.  For example, an automake-like tool that filled
+  in default redo build rules for common program types would probably be
+  very popular.
+
+- Tell your friends!
+
+
+# Mailing list
+
+You should join the `redo-list@googlegroups.com` mailing list.
+
+You can find the mailing list archives here:
+<http://groups.google.com/group/redo-list>
+
+It might not look like it, but you can subscribe without having a
+Google Account.  Just send a message to
+`redo-list+subscribe@googlegroups.com` (note the plus sign).
+	
+It's okay to send a message directly to the mailing list
+without subscribing first.  If you reply to someone who writes to the
+list, please leave them in the cc: list, since if they
+haven't subscribed, they won't get your reply otherwise. 
+
+