Add tutorial for nbgitpuller

Fixes #50

docs/index.rst

@@ -34,6 +34,16 @@ Ubuntu 18.04. We have a bunch of tutorials to get you started.
   You should use this if your cloud provider does not already have a direct tutorial,
   or if you have experience setting up servers.
 
+Tutorials
+=========
+
+Tutorials guide you step-by-step through accomplishing a specific task.
+
+.. toctree::
+   :titlesonly:
+
+   tutorials/nbgitpuller.rst
+
 How-To Guides
 =============