Fix formatting of docstring example

It runs together in the built HTML.

Author: twm

html5lib/__init__.py

@@ -4,11 +4,11 @@
 HTML found in the wild and implements well-defined error recovery that
 is largely compatible with modern desktop web browsers.
 
-Example usage:
+Example usage::
 
-import html5lib
-f = open("my_document.html")
-tree = html5lib.parse(f)
+    import html5lib
+    f = open("my_document.html")
+    tree = html5lib.parse(f)
 """
 
 from __future__ import absolute_import, division, unicode_literals