Merge pull request #335 from nmuesch/patch-2

Adds section about updating the hostname/port

Author: LotharSee

docs/index.rst

@@ -37,7 +37,7 @@ for changing your code::
     Usage: [ENV_VARS] ddtrace-run <my_program>
 
 
-The available environment variables are:
+The available environment variables for `ddtrace-run` are:
 
 * ``DATADOG_TRACE_ENABLED=true|false`` (default: true): Enable web framework and library instrumentation. When false, your application code
   will not generate any traces.
@@ -112,6 +112,17 @@ small example that shows adding a custom span to a Flask application::
 
 Read the full `API`_ for more details.
 
+Modifying the Agent hostname and port
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+If the Datadog Agent is on a separate host from your application, you can modify the default ddtrace.tracer object to utilize another hostname and port. Here is a small example showcasing this::
+
+    from ddtrace import tracer
+    
+    tracer.configure(hostname=<YOUR_HOST>, port=<YOUR_PORT>)
+
+By default, these will be set to localhost and 8126 respectively. 
+
 Web Frameworks
 --------------