Adding doxygen setup and info for the testing framework.

Signed-off-by: Jon A. Cruz <jonc@osg.samsung.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
diff --git a/README b/README
index 97a552c..3fdfb37 100644
--- a/README
+++ b/README
@@ -18,6 +18,12 @@
 The test suite can be invoked via `make check`; see
 http://wayland.freedesktop.org/testing.html for additional details.
 
+Developer documentation can be built via `make doc`. Output will be in
+the build root under
+
+docs/developer/html/index.html
+docs/tools/html/index.html
+
 
 
 			Libweston