docs(tree): typo in comment (#12968)

A typo for word data in the comment

Author: MateMahinKhan

src/cdk/tree/tree.ts

@@ -76,7 +76,7 @@ export class CdkTree<T>
   /**
    * Provides a stream containing the latest data array to render. Influenced by the tree's
    * stream of view window (what dataNodes are currently on screen).
-   * Data source can be an observable of data array, or a dara array to render.
+   * Data source can be an observable of data array, or a data array to render.
    */
   @Input()
   get dataSource(): DataSource<T> | Observable<T[]> | T[] { return this._dataSource; }