Fix BillingAddress column definition in what's new (#5247)

Co-authored-by: Shay Rojansky <roji@roji.org>

Author: flcdrg

entity-framework/core/what-is-new/ef-core-10.0/whatsnew.md

@@ -304,7 +304,7 @@ CREATE TABLE [Customers] (
     [Id] int NOT NULL IDENTITY,
     [Name] nvarchar(max) NOT NULL,
     [ShippingAddress] json NOT NULL,
-    [BillingAddress] json NOT NULL NULL,
+    [BillingAddress] json NOT NULL,
     CONSTRAINT [PK_Customers] PRIMARY KEY ([Id])
 );
 ```