Code fence the null keyword (#16750)

Author: pkulikov

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

@@ -12,7 +12,7 @@ ms.assetid: fecb1c60-6232-4efe-87f7-9a86ba2e9119
 
 The `null` keyword is a literal that represents a null reference, one that does not refer to any object. `null` is the default value of reference-type variables. Ordinary value types cannot be null, except for [nullable value types](../builtin-types/nullable-value-types.md).
 
-The following example demonstrates some behaviors of the null keyword:
+The following example demonstrates some behaviors of the `null` keyword:
 
 [!code-csharp[csrefKeywordsLiteral#1](~/samples/snippets/csharp/VS_Snippets_VBCSharp/csrefKeywordsLiteral/CS/csrefKeywordsLiteral.cs#1)]