.NET 10 P6 - CSharp (#9943)

* Add period to last sentence in csharp preview6 release notes.

* update C#

Author: jamesmontemagno

release-notes/10.0/preview/preview6/csharp.md

@@ -1,14 +1,8 @@
-# C# 14 updates in .NET 10 Preview 63 - Release Notes
+# C# 14 updates in .NET 10 Preview 6 - Release Notes
 
-Here's a summary of what's new in C# in this preview release:
-
-- [Feature](#feature)
+This preview release does not contain new C# features.
 
 C# 14 updates:
 
 - [What's new in C# 14](https://learn.microsoft.com/dotnet/csharp/whats-new/csharp-14) documentation
 - [Breaking changes in C# 14](https://learn.microsoft.com/dotnet/csharp/whats-new/breaking-changes/compiler%20breaking%20changes%20-%20dotnet%2010)
-
-## Feature
-
-Something about the feature