Enable heading permalinks with unicode-aware TOC slugs

Add toc.permalink so readers can copy deep links to subsections, and use
slugify_unicode so non-Latin headings get stable readable anchors instead of #_1 fallbacks.

Author: arkid15r

mkdocs.yaml

@@ -41,6 +41,9 @@ markdown_extensions:
   - def_list
   - attr_list
   - md_in_html
+  - toc:
+      permalink: true
+      slugify: !!python/name:markdown.extensions.toc.slugify_unicode
 
 plugins:
   - open-in-new-tab