add project README

Now that we're using GitLab, let's take advantage of the "landing page"
README feature with some minimal information, mostly to point people to
the right resources.

Acked-by: Dylan Baker <dylan@pnwbakers.com>
Acked-by: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Eric Engestrom <eric.engestrom@intel.com>

README.rst

@@ -0,0 +1,76 @@
+`Mesa <https://mesa3d.org>`_ - The 3D Graphics Library
+======================================================
+
+
+Source
+------
+
+This repository lives at https://gitlab.freedesktop.org/mesa/mesa.
+Other repositories are likely forks, and code found there is not supported.
+
+
+Build status
+------------
+
+Travis:
+
+.. image:: https://travis-ci.org/mesa3d/mesa.svg?branch=master
+    :target: https://travis-ci.org/mesa3d/mesa
+
+Appveyor:
+
+.. image:: https://img.shields.io/appveyor/ci/mesa3d/mesa.svg
+    :target: https://ci.appveyor.com/project/mesa3d/mesa
+
+Coverity:
+
+.. image:: https://scan.coverity.com/projects/139/badge.svg?flat=1
+    :target: https://scan.coverity.com/projects/mesa
+
+
+Build & install
+---------------
+
+You can find more information in our documentation (`docs/install.html
+<https://mesa3d.org/install.html>`_), but the recommended way is to use
+Meson (`docs/meson.html <https://mesa3d.org/meson.html>`_):
+
+.. code-block:: sh
+
+  $ mkdir build
+  $ cd build
+  $ meson ..
+  $ sudo ninja install
+
+
+Support
+-------
+
+Many Mesa devs hang on IRC; if you're not sure which channel is
+appropriate, you should ask your question on `Freenode's #dri-devel
+<irc://chat.freenode.net#dri-devel>`_, someone will redirect you if
+necessary.
+Remember that not everyone is in the same timezone as you, so it might
+take a while before someone qualified sees your question.
+
+The next best option is to ask your question in an email to the
+mailing lists: `mesa-dev\@lists.freedesktop.org
+<https://lists.freedesktop.org/mailman/listinfo/mesa-dev>`_
+
+
+Bug reports
+-----------
+
+If you think something isn't working properly, please file a bug report
+(`docs/bugs.html <https://mesa3d.org/bugs.html>`_).
+
+
+Contributing
+------------
+
+Contributions are welcome, and step-by-step instructions can be found in our
+documentation (`docs/submittingpatches.html
+<https://mesa3d.org/submittingpatches.html>`_).
+
+Note that Mesa uses email mailing-lists for patches submission, review and
+discussions.