some more documentation updates and minor code cleanups.  Additionally True and true in the template are the same now, same for false/False and none/None.

--HG--
branch : trunk
diff --git a/docs/sandbox.rst b/docs/sandbox.rst
index f6ec78c..bb0ca9f 100644
--- a/docs/sandbox.rst
+++ b/docs/sandbox.rst
@@ -29,3 +29,18 @@
 .. autofunction:: is_internal_attribute
 
 .. autofunction:: modifies_known_mutable
+
+.. admonition:: Note
+
+    The Jinja2 sandbox alone is no solution for perfect security.  Especially
+    for web applications you have to keep in mind that users may create
+    templates with arbitrary HTML in so it's crucial to ensure that (if you
+    are running multiple users on the same server) they can't harm each other
+    via JavaScript insertions and much more.
+
+    Also the sandbox is only as good as the configuration.  We stronly
+    recommend only passing non-shared resources to the template and use
+    some sort of whitelisting for attributes.
+
+    Also keep in mind that templates may raise runtime or compile time errors,
+    so make sure to catch them.