Mention the Jupyter Lite deployment on the read the docs homepage (#275)

* Mention the Jupyter Lite deployment on the read the docs homepage

Author: mcbarton

docs/source/index.rst

@@ -12,7 +12,11 @@ Introduction
 ------------
 
 ``xeus-cpp`` is a Jupyter kernel for cpp based on the native implementation of
-the Jupyter protocol xeus_.
+the Jupyter protocol xeus_. Try a Jupyter Lite demo of xeus-cpp by clicking
+
+.. image:: https://jupyterlite.rtfd.io/en/latest/_static/badge.svg
+   :target: https://compiler-research.github.io/xeus-cpp/lab/index.html
+   :alt: lite-badge
 
 Licensing
 ---------
@@ -40,4 +44,4 @@ The Xeus-Cpp is a Jupyter kernel for the C++ programming language
    FAQ
    reference
 
-.. _xeus: https://github.com/jupyter-xeus/xeus
+.. _xeus: https://github.com/jupyter-xeus/xeus