Initial commit for the official OP-TEE documentation

This initial commit brings in all existing documentation found across
various gits making up the documentation for the OP-TEE project. So in
summary what this includes and what has been done is:

- Import all old documentation (optee_os, optee_client, optee_test and
  so on).
- Convert everything from markdown (*.md) to reStructuredText (*.rst).
- Add a couple of new pages (optee_docs, disclosure policy to name a
  few).
- Add Sphinx configuration.
- Add Travis configuration to enable automatic testing of future
  documentation patches.
- Finally, a general clean-up and verification of content,
  links as well as verification of build instructions etc has also been
  done.
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..a251f98
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,23 @@
+# Minimal makefile for Sphinx documentation
+#
+#
+# You can set these variables from the command line.
+SPHINXOPTS    =
+SPHINXBUILD   ?= sphinx-build
+SPHINXPROJ    = OP-TEE
+SOURCEDIR     = .
+BUILDDIR      = _build
+
+# Put it first so that "make" without argument is like "make help".
+help:
+	@$(SPHINXBUILD) -M help "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
+
+.PHONY: help Makefile clean
+
+# Catch-all target: route all unknown targets to Sphinx using the new
+# "make mode" option.  $(O) is meant as a shortcut for $(SPHINXOPTS).
+%: Makefile
+	@$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
+
+clean:
+	rm -rf $(BUILDDIR)