adding readme and master branch.

Author: Sam Kleinman

README.rst

@@ -0,0 +1,11 @@
+============================
+Documentation Project Assets
+============================
+
+This repository hosts images and other assets for MongoDB
+documentation projects. The build system for relevant sites, clones
+this repository and checks out the appropriate branch for the
+production site.
+
+All images in the MongoDB manual, with two exceptions, are generated
+at build time from svg sources.