fix typo

docs/csharp/toc.yml

@@ -674,7 +674,7 @@ items:
       href: programming-guide/generics/generics-in-the-run-time.md
 - name: Other C# documentation
   items:
-  - name: C# anguage reference
+  - name: C# language reference
     href: ./language-reference/index.yml
   - name: C# specification
     href: ./specification/index.yml