Add description of ExcuTorch main page

Signed-off-by: Chris Abraham <[email protected]>

Author: cjyabraham

executorch.html

@@ -4,6 +4,7 @@
 body-class: announcement
 background-class: announcement-background
 permalink: /executorch-overview
+excerpt: Learn about executorch, a mobile machine learning framework within PyTorch for deploying deep learning models on mobile and embedded devices.
 ---
 
 <div class="container">