📝 docs(concepts): update course overview slug

- change slug from '/concepts' to '/' for better accessibility
- ensure the main course page is correctly routed

Author: vicegd

concepts/00-index.mdx

@@ -1,7 +1,7 @@
 ---
 sidebar_position: 0
 title: Course Overview
-slug: /concepts
+slug: /
 ---
 
 import ConceptIndex from '@site/src/components/ConceptIndex';