Update README.rst (#329)

Add direct link to PyPi and change badge to be from the same source (shields.io) for consistency.

README.rst

diff --git a/README.rst b/README.rst
index 040ab38..b65ae72 100644
--- a/README.rst
+++ b/README.rst
@@ -2,8 +2,8 @@
 TOML
 ****
 
-.. image:: https://badge.fury.io/py/toml.svg
-    :target: https://badge.fury.io/py/toml
+.. image:: https://img.shields.io/pypi/v/toml
+    :target: https://pypi.org/project/toml/
 
 .. image:: https://travis-ci.org/uiri/toml.svg?branch=master
     :target: https://travis-ci.org/uiri/toml