Fix link to sentry-python in README (#1304)

Author: 0xdiba

README.rst

@@ -33,7 +33,7 @@ Raven - Sentry for Python
 Raven is the official legacy Python client for `Sentry`_, officially supports
 Python 2.6–2.7 & 3.3–3.7, and runs on PyPy and Google App Engine.
 
-**This SDK is being phased out for `Sentry-Python <https://github.com/getsentry/sentry-python>`__**
+**This SDK is being phased out for** `Sentry-Python <https://github.com/getsentry/sentry-python>`_.
 
 It tracks errors and exceptions that happen during the
 execution of your application and provides instant notification with detailed