add usage example from cli; thanks to Christian Clauss from docs@
diff --git a/Doc/library/webbrowser.rst b/Doc/library/webbrowser.rst
index 56c444d..e6e7ea2 100644
--- a/Doc/library/webbrowser.rst
+++ b/Doc/library/webbrowser.rst
@@ -36,7 +36,9 @@
module. It accepts an URL as the argument. It accepts the following optional
parameters: ``-n`` opens the URL in a new browser window, if possible;
``-t`` opens the URL in a new browser page ("tab"). The options are,
-naturally, mutually exclusive.
+naturally, mutually exclusive. Usage example::
+
+ python -m webbrowser -t "http://www.python.org"
The following exception is defined: