Update mediator.mdx

Author: aritchie

src/content/docs/release-notes/mediator.mdx

@@ -15,7 +15,41 @@ import RN from '/src/components/ReleaseNote.astro';
 <RN type="enhancement">New RuntimeEventRegistration service that you can add event handlers to at runtime dynamically</RN>
 <RN type="fix">Child context should not receive a copy of the parent's headers as this will crash things like caching for a child request</RN>
 
-#### New Contract Key Generator
+#### New JSON Converter Source Generator
+This feature allows you to generate JSON converters at compile time instead of using reflection at runtime.  This is especially useful for AOT scenarios like iOS and Blazor WebAssembly.
+Unfortunately, we are unable to "piggyback" source generators (ours to System.Text.Json), so we found the easiest way to do this was to generate JSON converters, NOT the types emitted by the System.Text.Json source generator.
+
+Setting JSON converters allow you to push JsonConverterAttribute on the type instead of having to pass around a centralized JSON context.  
+
+We have two flavours of JSON generation.  The first one (and most importantly) is for our HTTP client code generation.  NOTE that JsonConverter generation is NOT enabled by default yet.
+
+```xml
+<ItemGroup>
+  <MediatorHttp Include="OpenApiRemote" 
+                Uri="https://youruri" 
+                GenerateJsonConverters="true"
+                Visible="false" />
+</ItemGroup>
+```
+
+Secondly, there will be times for features such as offline data storage or caching where data needs to serialize down to disk.  These types obviously aren't generated by our source generators and are likely
+types you've created.  We've created a secondary way to create JSON converters for your own types.
+
+```csharp
+[SourceGenerateJsonConverter]
+public partial class YourClass 
+{
+  public string? Name { get; set; }
+  public int Age { get; set; }
+}
+```
+
+NOTE: Your class must be partial and the attribute must be placed on the type directly.
+
+
+#### New Contract Key Source Generator
+This feature allows you to generate a contract key at compile time instead of using reflection at runtime.  This is especially useful for AOT scenarios like iOS and Blazor WebAssembly.
+
 * Type must be partial
 * Keys support property names with formatting (like DateTime)
 * If no key is specified, it will generate a key format for all public instance properties that are not null