docs: decorate method names with '``'

Author: kenjis

user_guide_src/source/concepts/http.rst

@@ -98,7 +98,7 @@ is an object-oriented representation of the HTTP request. It provides everything
     $request->getMethod();  // get, post, put, etc
 
 The request class does a lot of work in the background for you, that you never need to worry about.
-The `isAJAX()` and `isSecure()` methods check several different methods to determine the correct answer.
+The ``isAJAX()`` and ``isSecure()`` methods check several different methods to determine the correct answer.
 
 .. 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.