update changelog & readme

src/packages/excalidraw/CHANGELOG.md

@@ -21,7 +21,7 @@ Please add the latest change on the top under the correct section.
 
   - File data are encoded as DataURLs (base64) for portability reasons.
 
-  [ExcalidrawAPI](https://github.com/excalidraw/excalidraw/blob/master/src/packages/excalidraw/README.md#onLibraryChange):
+  [ExcalidrawAPI](https://github.com/excalidraw/excalidraw/blob/master/src/packages/excalidraw/README.md#ref):
 
   - added `getFiles()` to get current `BinaryFiles` (`Record<FileId, BinaryFileData>`). It may contain files that aren't referenced by any element, so if you're persisting the files to a storage, you should compare them against stored elements.
 
@@ -37,6 +37,8 @@ Please add the latest change on the top under the correct section.
   - `.excalidraw` files may now contain top-level `files` key in format of `Record<FileId, BinaryFileData>` when exporting any (image) elements.
   - Changes were made to various export utilityies exported from the package so that they take `files`. For now, TypeScript should help you figure the changes out.
 
+- Expose App instance from [ExcalidrawAPI](https://github.com/excalidraw/excalidraw/blob/master/src/packages/excalidraw/README.md#ref) [#4088](https://github.com/excalidraw/excalidraw/pull/4088).
+
 ## Excalidraw API
 
 ### Features

src/packages/excalidraw/README_NEXT.md

@@ -449,6 +449,7 @@ You can pass a `ref` when you want to access some excalidraw APIs. We expose the
 | --- | --- | --- |
 | ready | `boolean` | This is set to true once Excalidraw is rendered |
 | readyPromise | [resolvablePromise](https://github.com/excalidraw/excalidraw/blob/master/src/utils.ts#L317) | This promise will be resolved with the api once excalidraw has rendered. This will be helpful when you want do some action on the host app once this promise resolves. For this to work you will have to pass ref as shown [here](#readyPromise) |
+| [app](#app) | [`InstanceType<typeof App>`](https://github.com/excalidraw/excalidraw/blob/master/src/components/App.tsx) | Excalidraw App instance |
 | [updateScene](#updateScene) | <pre>(scene: <a href="https://github.com/excalidraw/excalidraw/blob/master/src/types.ts#L207">sceneData</a>) => void </pre> | updates the scene with the sceneData |
 | [addFiles](#addFiles) | <pre>(files: <a href="https://github.com/excalidraw/excalidraw/blob/master/src/types.ts">BinaryFileData</a>) => void </pre> | add files data to the appState |
 | resetScene | `({ resetLoadingState: boolean }) => void` | Resets the scene. If `resetLoadingState` is passed as true then it will also force set the loading state to false. |
@@ -470,6 +471,10 @@ const excalidrawRef = { current: { readyPromise: <a href="https://github.com/exc
 
 Since plain object is passed as a `ref`, the `readyPromise` is resolved as soon as the component is mounted. Most of the time you will not need this unless you have a specific use case where you can't pass the `ref` in the react way and want to do some action on the host when this promise resolves. You can check the [example](https://codesandbox.io/s/eexcalidraw-resolvable-promise-d0qg3?file=/src/App.js) for the usage.
 
+#### `app`
+
+The App instance. Generally, you shouldn't need to use this, but there may be cases you need to do something for which we don't yet expose a public API.
+
 ### `updateScene`
 
 <pre>