config: Update avatar and add square logo

Author: CohenArthur

_config.yml

@@ -66,7 +66,7 @@ theme_mode: dark # [light|dark]
 # img_cdn: "https://chirpy-img.netlify.app"
 
 # the avatar on sidebar, support local or CORS resources
-# avatar: "/commons/avatar.jpg"
+avatar: "images/logo_square.png"
 
 # boolean type, the global switch for TOC in posts.
 # toc: true