Update changelog with render arg info

Author: greglittlefield-wf

CHANGELOG.md

@@ -11,7 +11,7 @@ Breaking change - fix nullability/typings for `ReactDom.findDomNode` and `ReactD
 
 The previous typings were incorrect:
 - `findDOMNode` returns null in many cases, but its return type was incorrectly non-nullable.
-- `render` returns null for some cases (function components, `null`), `Element` for DOM components, and `CharacterData` for strings and numbers, but was incorrectly typed as non-nullable `ReactComponent`.
+- `render` returns null for some cases (function components, `null`), `Element` for DOM components, and `CharacterData` for strings and numbers, but was incorrectly typed as non-nullable `ReactComponent`. The `component` argument also accepts `null` and other "ReactNode" arguments to rendered, but its type is incorrectly non-nullable and restricted to just `ReactElement`.
 
 These typings only affect these APIs under the `ReactDom` class in package:react/react_client/react_interop.dart, and not the top-level `Function`-typed `findDOMNode` and `render` APIs exported from `package:react/react_dom.dart`, which most consumers use.