[pyramid] update documentation

Author: Emanuele Palazzetti

ddtrace/contrib/pyramid/__init__.py

@@ -15,6 +15,12 @@
     # use your config as normal.
     config.add_route('index', '/')
 
+Available settings are:
+
+* `datadog_trace_service`: change the `pyramid` service name
+* `datadog_trace_enabled`: sets if the Tracer is enabled or not
+* `datadog_distributed_tracing`: set it to `True` to enable Distributed Tracing
+
 If you use the 'pyramid.tweens' settings value to set the tweens for your
 application, you need to add 'ddtrace.contrib.pyramid:trace_tween_factory'
 explicitly to the list. For example::