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/release-notes/index.rst b/doc/release-notes/index.rst
new file mode 100644
index 0000000..605350d
--- /dev/null
+++ b/doc/release-notes/index.rst
@@ -0,0 +1,10 @@
+.. _release-notes:
+
+op-build Release Notes
+======================
+
+.. toctree::
+   :maxdepth: 1
+
+   v1.21-rc1
+   v1.21-rc2