chore: add def_list MkDocs extension (#238)

Aligns with Python, Go, Ruby, and Rust repos which all have def_list configured.

Co-authored-by: wphillipmoore-claude <255925739+wphillipmoore-claude@users.noreply.github.com>

Author: wphillipmoore

docs/site/mkdocs.yml

@@ -42,6 +42,7 @@ plugins:
 
 markdown_extensions:
   - admonition
+  - def_list
   - pymdownx.details
   - pymdownx.highlight:
       anchor_linenums: true