[docs] Performance tutorial (huggingface#2773)

* update performance tutorial

* fix divs

* oops forgot to close tag

* apply feedback

* apply feedback

* apply feedback

* align doc title

Author: stevhliu

docs/source/en/_toctree.yml

@@ -4,7 +4,7 @@
   - local: quicktour
     title: Quicktour
   - local: stable_diffusion
-    title: Stable Diffusion
+    title: Effective and efficient diffusion
   - local: installation
     title: Installation
   title: Get started