Update index.md to include atomic elements section (#339)

Added a note about atomic elements to the index.

Author: rami-elementor

src/data-structure/index.md

@@ -48,7 +48,8 @@ Special cases:
 * [Repeaters](./repeaters/)
 * [Global Styles](./global-styles/)
 
-Atomic Structure
+For information about atomic elements:
+
 * [Atomic Elements](./atomic-elements/)
 * [Atomic Widgets](./atomic-widgets/)
 * [Atomic Prop Values](./atomic-prop-values/)