[UG] Fix typo causing Sphinx warning "Literal block expected"

Author: LittleJ

user_guide_src/source/concepts/http.rst

@@ -99,8 +99,6 @@ The `isAJAX()` and `isSecure()` methods check several different methods to deter
 
 .. note:: The ``isAJAX()`` method depends on the ``X-Requested-With`` header, which in some cases is not sent by default in XHR requests via JavaScript (i.e. fetch). See the :doc:`AJAX Requests </general/ajax>` section on how to avoid this problem.
 
-::
-
 CodeIgniter also provides a :doc:`Response class </outgoing/response>` that is an object-oriented representation
 of the HTTP response. This gives you an easy and powerful way to construct your response to the client::