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/versioning.rst b/doc/versioning.rst
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index 0000000..d562b66
--- /dev/null
+++ b/doc/versioning.rst
@@ -0,0 +1,29 @@
+.. _versioning:
+
+Version Scheme
+==============
+
+Each firmware component has its own versioning scheme, and `op-build` brings
+all of these components together in one image with one global version
+number.
+
+Firmware versions are exposed to the user through both the device tree
+(:ref:`skiboot:device-tree/ibm,firmware-versions`) and the VERSION firmware
+partition. As such, firmware versioning numbers **MUST** follow the
+requirements in order for some functionality to be correct.
+
+skiboot
+  :ref:`skiboot:versioning`
+Hostboot
+  Currently just uses the git SHA1 of the commit
+OCC
+  Currently just uses the git SHA1 of the commit
+Petitboot
+  Uses a X.Y.Z versioning scheme.
+Linux
+  We use the upstream Linux kernel version, and always append ``-openpowerN``
+  where N is a number starting at 1 that increases for each change we make
+  to any additional patches carried in `op-build` for that specific kernel
+  version.
+  We follow the stable tree and have an "upstream *first*" policy in place.
+