Update docs for cakephp/cakephp#14246

Author: markstory

en/appendices/4-1-migration-guide.rst

@@ -59,6 +59,9 @@ View
 Behavior Changes
 ================
 
+While the following changes do not change the signature of any methods they do
+change the semantics or behavior of methods.
+
 Database
 --------
 
@@ -84,6 +87,16 @@ TestSuite
 
 * ``TestCase::setAppNamespace()`` now returns the previous app namespace for easier save and restore.
 
+View
+----
+
+* ``FormHelper`` now has its default value sources set to ``data, context``
+  instead of ``context``. If you use ``setValueSources()`` to changes the value
+  sources you may need to update your code.
+* The ``FormHelper`` Context classes provided by CakePHP no longer take
+  a ``$request`` object in their constructor anymore.
+
+
 New Features
 ============
 

en/views/helpers/form.rst

@@ -40,23 +40,21 @@ a following section. The built-in providers map to the following values of
 ``$context``:
 
 * An ``Entity`` instance or an iterator will map to
-  `EntityContext <https://api.cakephp.org/3.x/class-Cake.View.Form.EntityContext.html>`_;
+  `EntityContext
+  <https://github.com/cakephp/cakephp/tree/master/src/View/Form/EntityContext.php>`_;
   this context class allows FormHelper to work with results from the
   built-in ORM.
 
 * An array containing the ``'schema'`` key, will map to
-  `ArrayContext <https://api.cakephp.org/3.x/class-Cake.View.Form.ArrayContext.html>`_
+  `ArrayContext <https://github.com/cakephp/cakephp/tree/master/src/View/Form/ArrayContext.php>`_
   which allows you to create simple data structures to build forms against.
 
 * ``null`` and ``false`` will map to
-  `NullContext <https://api.cakephp.org/3.x/class-Cake.View.Form.NullContext.html>`_;
+  `NullContext <https://github.com/cakephp/cakephp/tree/master/src/View/Form/NullContext.php>`_;
   this context class
   simply satisfies the interface FormHelper requires. This context is useful if
   you want to build a short form that doesn't require ORM persistence.
 
-All context classes also have access to the request data, making it simpler to
-build forms.
-
 Once a form has been created with a context, all controls you create will use the
 active context. In the case of an ORM backed form, FormHelper can access
 associated data, validation errors and schema metadata. You can close the active
@@ -177,7 +175,7 @@ contexts, such as ``EntityContext``, will fetch data from ``$request->getData()`
 or from the current entity.
 
 If however, you are building a form that needs to read from the query string,
-you can use ``valueSource()`` to change where ``FormHelper`` reads data input
+you can use ``setValuesSource()`` to change where ``FormHelper`` reads data input
 data from::
 
     // Prioritize query string over context:
@@ -201,7 +199,8 @@ The supported sources are ``context``, ``data`` and ``query``. You can use one
 or more sources. Any widgets generated by ``FormHelper`` will gather their
 values from the sources, in the order you setup.
 
-The value sources will be reset to the default (``['context']``) when ``end()``
+The value sources will be reset to the default (``['data', 'context']``) when
+``end()``
 is called.
 
 Changing the HTTP Method for a Form