Update advanced.rst
break client side certificates out into a sub header
@@ -225,6 +225,9 @@ Requests can also ignore verifying the SSL certificate if you set ``verify`` to
By default, ``verify`` is set to True. Option ``verify`` only applies to host certs.
+Client side certificates
+------------------------
+
You can also specify a local cert to use as client side certificate, as a single
file (containing the private key and the certificate) or as a tuple of both
files' paths::
