update README

README.rst

@@ -3,3 +3,46 @@ Django-py-zipkin
 
 Django middleware and tracing utilities for submitting traces to Zipkin.
 py2 / py3 compatible.
+
+Usage
+~~~~~
+
+Set the settings, if not set it'll use defaults:
+
+*ZIPKIN_SERVICE_NAME*: ``unknown``
+    The name to use when identifying the service being traced.
+
+*ZIPKIN_TRANSPORT_HANDLER*: ``django_py_zipkin.transport.zipkin_transport``
+    Transport to use to submit traces to Zipkin. The default one submits
+    in the background via Celery.
+
+*ZIPKIN_ADD_LOGGING_ANNOTATION*: ``True``
+    Whether to add a 'logging_end' annotation when py_zipkin
+    finishes logging spans
+
+*ZIPKIN_TRACING_ENABLED*: ``False``
+    Whether or not to enable tracing, requires explicit enabling.
+
+*ZIPKIN_TRACING_SAMPLING*: ``1.00``
+    The sampling threshold
+
+*ZIPKIN_BLACKLISTED_PATHS*: ``[]``
+    List of regular expressions to ignore from tracing.
+
+Add the middleware
+
+::
+
+    MIDDLEWARE = [
+        ...
+        'django_py_zipkin.middleware.ZipkinMiddleware',
+        ...
+    ]
+
+Or instrument your code with the context manager::
+
+    with trace('span-name', request.zipkin_tracer) as context
+        traced_value = do_something_that_takes_time()
+        context.update({
+            'some.key': traced_value,
+        })