dt-bindings: arm: renesas: Document R-Car S4-8 SoC DT bindings

Add device tree bindings documentation for Renesas R-Car S4-8
(r8a779f0).

Signed-off-by: Yoshihiro Shimoda <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Geert Uytterhoeven <[e-mail]>

Documentation/devicetree/bindings/arm/renesas.yaml

···
           - const: renesas,falcon-cpu
           - const: renesas,r8a779a0
 
+      - description: R-Car S4-8 (R8A779F0)
+        items:
+          - const: renesas,r8a779f0
+
       - description: R-Car H3e (R8A779M0)
         items:
           - enum: