Update toc.yml for consistency (#43586)

Author: skycommand

docs/csharp/toc.yml

@@ -147,27 +147,30 @@ items:
 - name: What's new in C#
   items:
   - name: C# 13
-    displayName: what's New
-    href: whats-new/csharp-13.md
-  - name: Breaking changes since C# 12
-    href: ../../_roslyn/docs/compilers/CSharp/Compiler%20Breaking%20Changes%20-%20DotNet%209.md
+    items:
+    - name: What's new in C# 13
+      href: whats-new/csharp-13.md
+    - name: Breaking changes since C# 12
+      href: ../../_roslyn/docs/compilers/CSharp/Compiler%20Breaking%20Changes%20-%20DotNet%209.md
   - name: C# 12
-    displayName: what's New
-    href: whats-new/csharp-12.md
-  - name: Breaking changes since C# 11
-    href: ../../_roslyn/docs/compilers/CSharp/Compiler%20Breaking%20Changes%20-%20DotNet%208.md
+    items:
+    - name: What's new in C# 12
+      href: whats-new/csharp-12.md
+    - name: Breaking changes since C# 11
+      href: ../../_roslyn/docs/compilers/CSharp/Compiler%20Breaking%20Changes%20-%20DotNet%208.md
   - name: C# 11
     items:
-    - name: New features
-      displayName: what's new
+    - name: What's new C# 11
       href: whats-new/csharp-11.md
     - name: Breaking changes since C# 10
       href: ../../_roslyn/docs/compilers/CSharp/Compiler%20Breaking%20Changes%20-%20DotNet%207.md
   - name: C# 10
-    href: whats-new/csharp-10.md
-  - name: Breaking changes in earlier versions
-    href: whats-new/breaking-changes.md
-  - name: C# Version History
+    items:
+    - name: New features in C# 10
+      href: whats-new/csharp-10.md
+    - name: Breaking changes since earlier versions
+      href: whats-new/breaking-changes.md
+  - name: C# version history
     href: whats-new/csharp-version-history.md
   - name: Relationships to .NET library
     href: whats-new/relationships-between-language-and-library.md