DOC: Readme badges and formatting [skip ci]

Shiny, shiny badges!

README.rst

@@ -5,11 +5,19 @@ Widgets for the Jupyter notebook and JupyterLab
     :target: http://www.astropy.org
     :alt: Powered by Astropy Badge
 
-astrowidgets aims to be a set of astronomy widgets for Jupyter Lab or Notebook, leveraging the Astropy ecosystem.
+.. image:: https://travis-ci.org/astropy/astrowidgets.svg?branch=master
+    :target: https://travis-ci.org/astropy/astrowidgets
+    :alt: Travis CI Status
+
+.. image:: https://readthedocs.org/projects/astrowidgets/badge/?version=latest
+    :target: https://astrowidgets.readthedocs.io/en/latest/?badge=latest
+    :alt: Documentation Status
+
+``astrowidgets`` aims to be a set of astronomy widgets for Jupyter Lab or Notebook, leveraging the Astropy ecosystem.
 
 **Warning**
 
-astrowidgets is currently in *very* early development.  Nothing is guaranteed to work or do anything in particular 
+``astrowidgets`` is currently in *very* early development.  Nothing is guaranteed to work or do anything in particular 
 at this stage.