Fixed #17229 -- Allow 'True', 'False' and 'None' to resolve to the corresponding Python objects in templates.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17894 bcc190cf-cafb-0310-a4f2-bffc1f526a37

docs/ref/templates/api.txt

@@ -111,6 +111,9 @@ template::
     >>> t.render(c)
     "My name is Dolores."
 
+Variables and lookups
+~~~~~~~~~~~~~~~~~~~~~
+
 Variable names must consist of any letter (A-Z), any digit (0-9), an underscore
 (but they must not start with an underscore) or a dot.
 
@@ -225,7 +228,6 @@ straight lookups. Here are some things to keep in mind:
      if your variable is not callable (allowing you to access attributes of
      the callable, for example).
 
-
 .. _invalid-template-variables:
 
 How invalid variables are handled
@@ -263,6 +265,16 @@ be replaced with the name of the invalid variable.
     in order to debug a specific template problem, then cleared
     once debugging is complete.
 
+Builtin variables
+~~~~~~~~~~~~~~~~~
+
+Every context contains ``True``, ``False`` and ``None``. As you would expect,
+these variables resolve to the corresponding Python objects.
+
+.. versionadded:: 1.5
+    Before Django 1.5, these variables weren't a special case, and they
+    resolved to ``None`` unless you defined them in the context.
+
 Playing with Context objects
 ----------------------------