Add badges (#160)

Add badges

Author: betatim

README.rst

@@ -2,13 +2,31 @@
 Jupyter Server Proxy
 ====================
 
+|ReadTheDocs badge| |Travis badge| |PyPI badge| |Conda badge| |NPM badge|
+
+.. |ReadTheDocs badge| image:: https://img.shields.io/readthedocs/jupyter-server-proxy?logo=read-the-docs
+   :target: https://jupyter-server-proxy.readthedocs.io/
+
+.. |Travis badge| image:: https://img.shields.io/travis/jupyterhub/jupyter-server-proxy/master.svg?logo=travis
+   :target: https://travis-ci.org/jupyterhub/jupyter-server-proxy
+
+.. |PyPI badge| image:: https://img.shields.io/pypi/v/jupyter-server-proxy.svg?logo=pypi
+   :target: https://pypi.python.org/pypi/jupyter-server-proxy
+
+.. |Conda badge| image:: https://img.shields.io/conda/vn/conda-forge/jupyter-server-proxy?logo=conda-forge
+   :target: https://anaconda.org/conda-forge/jupyter-server-proxy
+
+.. |NPM badge| image:: https://img.shields.io/npm/v/jupyterlab-server-proxy.svg?logo=npm
+   :target: https://www.npmjs.com/package/jupyterlab-server-proxy
+
 Jupyter Server Proxy lets you run arbitrary external processes (such
 as RStudio, Shiny Server, syncthing, PostgreSQL, etc) alongside your
 notebook, and provide authenticated web access to them.
 
-**Note:** This project used to be called **nbserverproxy**. if you have an older
-version of nbserverproxy installed, remember to uninstall it before install
-jupyter-server-proxy - otherwise they may conflict
+**Note:** This project used to be called **nbserverproxy**. As
+nbserverproxy is an older version of jupyter-server-proxy, uninstall
+nbserverproxy before installing jupyter-server-proxy to avoid
+conflicts.
 
 The primary use cases are:
 
@@ -32,18 +50,26 @@ Install
 pip
 ---
 
-``pip install jupyter-server-proxy``
+.. code-block::
+
+   pip install jupyter-server-proxy
 
 conda
 -----
 
-``conda install jupyter-server-proxy -c conda-forge``
+.. code-block::
+
+   conda install jupyter-server-proxy -c conda-forge
 
 src
 ---
 
-``pip install .``
+.. code-block::
+
+   pip install .
 
 **Note:** if installing from source in editable mode: ``setup.py develop/pip install -e``, please explicitly install the server extensions:
 
-``jupyter serverextension enable --sys-prefix jupyter_server_proxy``
+.. code-block::
+
+   jupyter serverextension enable --sys-prefix jupyter_server_proxy