Merge pull request #2167 from jpadilla/patch-1

Change allow_none to allow_null in 3.0 announcement

Author: xordoquy

docs/topics/3.0-announcement.md

@@ -557,22 +557,22 @@ We now use the following:
 * `Field` is the base class for all fields. It does not include any default implementation for either serializing or deserializing data.
 * `ReadOnlyField` is a concrete implementation for read-only fields that simply returns the attribute value without modification.
 
-#### The `required`, `allow_none`, `allow_blank` and `default` arguments.
+#### The `required`, `allow_null`, `allow_blank` and `default` arguments.
 
 REST framework now has more explicit and clear control over validating empty values for fields.
 
 Previously the meaning of the `required=False` keyword argument was underspecified. In practice its use meant that a field could either be not included in the input, or it could be included, but be `None` or the empty string.
 
-We now have a better separation, with separate `required`, `allow_none` and `allow_blank` arguments.
+We now have a better separation, with separate `required`, `allow_null` and `allow_blank` arguments.
 
 The following set of arguments are used to control validation of empty values:
 
 * `required=False`: The value does not need to be present in the input, and will not be passed to `.create()` or `.update()` if it is not seen.
 * `default=<value>`: The value does not need to be present in the input, and a default value will be passed to `.create()` or `.update()` if it is not seen.
-* `allow_none=True`: `None` is a valid input.
+* `allow_null=True`: `None` is a valid input.
 * `allow_blank=True`: `''` is valid input. For `CharField` and subclasses only.
 
-Typically you'll want to use `required=False` if the corresponding model field has a default value, and additionally set either `allow_none=True` or `allow_blank=True` if required.
+Typically you'll want to use `required=False` if the corresponding model field has a default value, and additionally set either `allow_null=True` or `allow_blank=True` if required.
 
 The `default` argument is also available and always implies that the field is not required to be in the input. It is unnecessary to use the `required` argument when a default is specified, and doing so will result in an error.