Add keras stable-diffusion to tensorflow.org

PiperOrigin-RevId: 494204840

Author: MarkDaoust

site/en/tutorials/_toc.yaml

@@ -180,6 +180,9 @@ toc:
 - title: "Generative"
   style: accordion
   section:
+  - title: "Stable Diffusion"
+    status: new
+    path: /tutorials/generative/generate_images_with_stable_diffusion
   - title: "Neural style transfer"
     path: /tutorials/generative/style_transfer
   - title: "DeepDream"