Document method spoofing. Fixes #1668

Author: lonnieezell

user_guide_src/source/incoming/index.rst

@@ -13,4 +13,5 @@ Controllers handle incoming requests.
     message
     request
     incomingrequest
-    content_negotiation
+    content_negotiation
+    methodspoofing

user_guide_src/source/incoming/methodspoofing.rst

@@ -0,0 +1,24 @@
+====================
+HTTP Method Spoofing
+====================
+
+When working with HTML forms you can only use GET or POST HTTP verbs. In most cases this is just fine. However, to
+support REST-ful routing you need to support other, more correct, verbs, like DELETE or PUT. Since the browsers
+don't support this, CodeIgniter provides you with a way to spoof the method that is being used. This allows you to
+make a POST request, but tell the application that it should be treated as a different request type.
+
+To spoof the method, a hidden input is added to the form with the name of ``_method``. It's value is the HTTP verb
+that you want the request to be::
+
+    <form action="" method="post">
+        <input type="hidden" name="_method" value="PUT" />
+
+    </form>
+
+This form is converted into a PUT request and is a true PUT request as far as the routing and the IncomingRequest
+class are concerned.
+
+The form that you are using must be a POST request. GET requests cannot be spoofed.
+
+.. note:: Be sure to check your web server's configuration as some servers do not support all HTTP verbs
+    with the default configuration, and must have additional packages enabled to work.