Add badges: Travis, RTD, PyPI, PyVersions.

Also, point to RTD for docs.

[ci skip]

README.rst

@@ -2,9 +2,24 @@
 Transactions
 ============
 
+.. image:: https://travis-ci.org/zopefoundation/transaction.png?branch=master
+        :target: https://travis-ci.org/zopefoundation/transaction
+
+.. image:: https://readthedocs.org/projects/transaction/badge/?version=latest
+        :target: http://transaction.readthedocs.org/en/latest/
+        :alt: Documentation Status
+
+.. image:: https://img.shields.io/pypi/v/transaction.svg
+        :target: https://pypi.python.org/pypi/transaction
+        :alt: PyPI
+
+.. image:: https://img.shields.io/pypi/pyversions/transaction.svg
+        :target: https://pypi.python.org/pypi/transaction
+        :alt: Python versions
+
 This package contains a generic transaction implementation for Python. It is
 mainly used by the ZODB.
 
-See http://zodb.readthedocs.org/en/latest/transactions.html for narrative
-documentation on its usage.
+See http://transaction.readthedocs.org/en/latest for narrative documentation
+on its usage.