Update sealed.md with sealing methods from Object class (#44196)

* Update sealed.md with sealing methods from Object class

It was introduced in C# 10. There is possibility to prevent overriding of ToString() and the rest of Object's virtual methods

* Update sealed.md

corrected hrefs

* Update sealed.md

Fixed link to what's-new

* Update sealed.md

there was still too much '/' backtracking in the whats-new link

* Update docs/csharp/language-reference/keywords/sealed.md

Co-authored-by: Bill Wagner <[email protected]>

---------

Co-authored-by: Bill Wagner <[email protected]>

Author: theluckyprogrammer

docs/csharp/language-reference/keywords/sealed.md

@@ -27,6 +27,11 @@ In the following example, `Z` inherits from `Y` but `Z` cannot override the virt
 [!code-csharp[csrefKeywordsModifiers#16](~/samples/snippets/csharp/VS_Snippets_VBCSharp/csrefKeywordsModifiers/CS/csrefKeywordsModifiers.cs#16)]
 
 When you define new methods or properties in a class, you can prevent deriving classes from overriding them by not declaring them as [virtual](virtual.md).
+When you override a `virtual` member declared in a base type, you can prevent deriving types from overriding them by using sealed keyword as in the following example:
+
+```
+public sealed override string ToString() => Value;
+```
 
 It is an error to use the [abstract](abstract.md) modifier with a sealed class, because an abstract class must be inherited by a class that provides an implementation of the abstract methods or properties.