Improve vagrant-onap documentation

It was added the process to create documentation thru sphinx tool.
Now it's possible to generate all the documentation locally running:

$ tox -e docs

Lastly, the installation guide was included as a reference to
different methods to install requirements.

Change-Id: Id0b277d605cf83ddbde54ecd9f4648e1f89023c3
Signed-off-by: Victor Morales <victor.morales@intel.com>
diff --git a/bootstrap/vagrant-onap/doc/source/index.rst b/bootstrap/vagrant-onap/doc/source/index.rst
index 88950a2..509f348 100644
--- a/bootstrap/vagrant-onap/doc/source/index.rst
+++ b/bootstrap/vagrant-onap/doc/source/index.rst
@@ -17,5 +17,6 @@
 .. toctree::
    :maxdepth: 2
 
-   Advanced Features <features/index>
+   Installation Guide <install/index>
+   Advanced Features <features/features>