doc: Add basic Sphinx configuration and Makefile

Adding the same type of Sphinx config that is used for the main
TF-A repo. Contains the config itself, a Makefile to build the
docs directly under the /docs directory (not tied to top-level
Makefile by design), an index page and the TF.org logo as used
in TF-A.

Change-Id: Ifd5c83533fbad457b448a52f42a2f12303887f4a
Signed-off-by: Paul Beesley <paul.beesley@arm.com>
diff --git a/docs/index.rst b/docs/index.rst
new file mode 100644
index 0000000..8a32608
--- /dev/null
+++ b/docs/index.rst
@@ -0,0 +1,17 @@
+Trusted Firmware-A Tests Documentation
+======================================
+
+.. toctree::
+   :maxdepth: 1
+   :hidden:
+
+   Home<self>
+   user-guide
+   porting-guide
+   implementing-tests
+   design
+   change-log
+
+--------------
+
+*Copyright (c)2019, Arm Limited. All rights reserved.*