Remove outdated note and added support period for .NET 10 (dotnet#10172)

Updated the support duration for .NET 10 to specify three years from November 11, 2025 to November 14, 2028.

Author: mairaw

release-notes/10.0/README.md

@@ -1,8 +1,6 @@
 # .NET 10
 
-.NET 10 is a [Long Term Support (LTS)](../../release-policies.md) release and will be supported on [multiple operating systems](supported-os.md) for 36 months.
-
-It is currently in development and not supported. .NET 10 is expected to be released in late 2025.
+.NET 10 is a [Long Term Support (LTS)](../../release-policies.md) release and will be supported on [multiple operating systems](supported-os.md) for three years from November 11, 2025 to November 14, 2028.
 
 - [Downloads](https://dotnet.microsoft.com/download/dotnet/10.0)
 - [Linux Package Managers](https://learn.microsoft.com/dotnet/core/install/linux)