Correct formatting and wording in nullable annotations doc

Author: gewarren

docs/standard/serialization/system-text-json/nullable-annotations.md

@@ -85,20 +85,20 @@ record MyPoco(
     );
 ```
 
-## Missing values vs. null values
+## Missing values versus null values
 
-It's important to understand the distinction between missing JSON properties and properties with explicit `null` values when using <xref:System.Text.Json.JsonSerializerOptions.RespectNullableAnnotations>. JavaScript distinguishes between `undefined` (missing property) and `null` (explicit null value). However, .NET doesn't have an `undefined` concept, so both cases deserialize to `null` in .NET.
+It's important to understand the distinction between *missing JSON properties* and *properties with explicit `null` values* when you set <xref:System.Text.Json.JsonSerializerOptions.RespectNullableAnnotations>. JavaScript distinguishes between `undefined` (missing property) and `null` (explicit null value). However, .NET doesn't have an `undefined` concept, so both cases deserialize to `null` in .NET.
 
-When `RespectNullableAnnotations` is `true`:
+During deserialization, when `RespectNullableAnnotations` is `true`:
 
-- **Explicit null value**: Throws an exception for non-nullable properties. For example, `{"Name":null}` throws an exception when deserializing to a non-nullable `string Name` property.
-- **Missing property**: Does NOT throw an exception, even for non-nullable properties. For example, `{}` does not throw an exception when deserializing to a non-nullable `string Name` property. The property is set to `null`.
+- An **explicit null value** throws an exception for non-nullable properties. For example, `{"Name":null}` throws an exception when deserializing to a non-nullable `string Name` property.
+- A **missing property** doesn't throw an exception, even for non-nullable properties. For example, `{}` doesn't throw an exception when deserializing to a non-nullable `string Name` property. The property is set to `null`.
 
-The following code demonstrates this difference:
+  The following code shows how a missing property does NOT throw an exception during deserialization:
 
-:::code language="csharp" source="snippets/nullable-annotations/Nullable.cs" id="MissingVsNull":::
+  :::code language="csharp" source="snippets/nullable-annotations/Nullable.cs" id="MissingVsNull":::
 
-This behavior occurs because missing properties are treated as optional (not provided), while explicit `null` values are treated as provided values that violate the non-nullable constraint. If you need to enforce that a property must be present in the JSON, use the `required` modifier or configure the property as required using <xref:System.Text.Json.Serialization.JsonRequiredAttribute> or the contracts model.
+This behavior difference occurs because missing properties are treated as optional (not provided), while explicit `null` values are treated as provided values that violate the non-nullable constraint. If you need to enforce that a property must be present in the JSON, use the `required` modifier or configure the property as required using <xref:System.Text.Json.Serialization.JsonRequiredAttribute> or the contracts model.
 
 ## See also