docs: Remove unreleased link as its already available (#3212)

src/packages/excalidraw/README.md

@@ -578,8 +578,6 @@ import { getElementsMap } from "@excalidraw/excalidraw";
 
 This function returns an object where each element is mapped to its id.
 
-**_The below api's will be available in [next version](https://github.com/excalidraw/excalidraw/blob/master/src/packages/excalidraw/CHANGELOG.md#unreleased)_**
-
 #### `restoreAppState`
 
 **_Signature_**