doc:fix

Author: cunla

mkdocs.yml

@@ -31,7 +31,7 @@ markdown_extensions:
   - pymdownx.details
   - pymdownx.emoji:
       emoji_generator: !!python/name:materialx.emoji.to_svg
-      emoji_index: !!python/name:materialx.emoji.twemoji
+      emoji_index: !!python/name:material.extensions.emoji.twemoji
   - pymdownx.highlight:
       anchor_linenums: true
   - pymdownx.inlinehilite