Update TreeView.md

unwanted comma removed

Author: ravichandran-blog

docs/documentation/docs/controls/TreeView.md

@@ -37,7 +37,7 @@ import { TreeView, ITreeItem } from "@pnp/spfx-controls-react/lib/TreeView";
     selectChildrenIfParentSelected={true}
     showCheckboxes={true}
     treeItemActionsDisplayMode={TreeItemActionsDisplayMode.ContextualMenu}
-    defaultSelectedKeys={['key1', 'key2']},
+    defaultSelectedKeys={['key1', 'key2']}
     expandToSelected={true}
     defaultExpandedChildren={true}
     onSelect={this.onTreeItemSelect}