Fix typo

That's all.

docs/topics/3.0-announcement.md

@@ -369,7 +369,7 @@ This class implements the same basic API as the `Serializer` class:
 * `.errors` - Returns an errors during validation.
 * `.save()` - Persists the validated data into an object instance.
 
-There are four mathods that can be overriding, depending on what functionality you want the serializer class to support:
+There are four methods that can be overridden, depending on what functionality you want the serializer class to support:
 
 * `.to_representation()` - Override this to support serialization, for read operations.
 * `.to_internal_value()` - Override this to support deserialization, for write operations.