Fixed #2181 -- allow '{' and '}' to be escaped via {% templatetag ... %}.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@3138 bcc190cf-cafb-0310-a4f2-bffc1f526a37

docs/templates.txt

@@ -766,6 +766,8 @@ The argument tells which template bit to output:
     ``closeblock``      ``%}``
     ``openvariable``    ``{{``
     ``closevariable``   ``}}``
+    ``openbrace``       ``{``
+    ``closebrace``      ``}``
     ==================  =======
 
 widthratio