Provide doc for signals.

docs/index.rst

@@ -34,6 +34,7 @@ Contents:
    sections/accesstokens
    sections/sessionmanagement
    sections/settings
+   sections/signals
    sections/examples
    sections/contribute
 ..

docs/sections/signals.rst

@@ -0,0 +1,28 @@
+.. _signals:
+
+Signals
+#######
+
+Use signals in your application to get notified when some actions occur.
+
+For example::
+
+    from django.dispatch import receiver
+
+    from oidc_provider.signals import user_decline_consent
+
+
+    @receiver(user_decline_consent)
+    def my_callback(sender, **kwargs):
+        print(kwargs)
+        print('Ups! Some user has declined the consent.')
+
+user_accept_consent
+===================
+
+Sent when a user accept the authorization page for some client.
+
+user_decline_consent
+====================
+
+Sent when a user decline the authorization page for some client.