fix(docs): replace deprecated materialx.emoji.twemoji config

notice during mkdocs build:

    Material emoji logic has been officially moved into mkdocs-material
    version 9.4. Please use Material's 'material.extensions.emoji.twemoji'
    instead of 'materialx.emoji.twemoji' in your 'mkdocs.yml' file.

    ```
    markdown_extensions:
    - pymdownx.emoji:
        emoji_index: !!python/name:material.extensions.emoji.twemoji
        emoji_generator: !!python/name:material.extensions.emoji.to_svg
    ```

    'mkdocs_material_extensions' is deprecated and will no longer be
    supported moving forward. This is the last release.

Author: thekaveman

mkdocs.yml

@@ -44,8 +44,8 @@ markdown_extensions:
   - meta
   - pymdownx.details
   - pymdownx.emoji:
-      emoji_index: !!python/name:materialx.emoji.twemoji
-      emoji_generator: !!python/name:materialx.emoji.to_svg
+      emoji_index: !!python/name:material.extensions.emoji.twemoji
+      emoji_generator: !!python/name:material.extensions.emoji.to_svg
   - pymdownx.inlinehilite
   - pymdownx.smartsymbols
   - pymdownx.superfences: