doc: initial sphinx-based documentation support

The release-notes script now produces Markdown compatible with
pandoc to help convert it into RST for sphinx.

Actual documentation is fairly limited currently.

We use intersphinx to link to various sub-projects' docs.

A .travis.yml file is added to build+publish documentation
when new code is pushed to github.

Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
diff --git a/doc/index.rst b/doc/index.rst
new file mode 100644
index 0000000..4bbc061
--- /dev/null
+++ b/doc/index.rst
@@ -0,0 +1,30 @@
+.. OpenPOWER Firmware documentation master file, created by
+   sphinx-quickstart on Thu Oct 12 14:38:45 2017.
+   You can adapt this file completely to your liking, but it should at least
+   contain the root `toctree` directive.
+
+Welcome to OpenPOWER Firmware's documentation!
+==============================================
+
+This documentation is for the ``op-build`` project, which is a buildroot
+overlay designed to build a full firmware image for OpenPOWER Systems.
+Individual firmware components will have their own documentation, which
+we link to where needed, but this document is focused on specifics to
+do with building the full firmware image.
+
+.. toctree::
+   :maxdepth: 2
+   :caption: Contents:
+
+   introduction
+   testing
+   process/index
+   versioning
+   release-notes/index
+
+Indices and tables
+==================
+
+* :ref:`genindex`
+* :ref:`modindex`
+* :ref:`search`