Added improved documentation to the `ContextReference` node.

--HG--
branch : trunk
diff --git a/jinja2/nodes.py b/jinja2/nodes.py
index 6720fb1..15461e8 100644
--- a/jinja2/nodes.py
+++ b/jinja2/nodes.py
@@ -821,7 +821,16 @@
 
 
 class ContextReference(Expr):
-    """Returns the current template context."""
+    """Returns the current template context.  It can be used like a
+    :class:`Name` node, with a ``'load'`` ctx and will return the
+    current :class:`~jinja2.runtime.Context` object.
+
+    Here an example that assigns the current template name to a
+    variable named `foo`::
+
+        Assign(Name('foo', ctx='store'),
+               Getattr(ContextReference(), 'name'))
+    """
 
 
 class Continue(Stmt):