Update 0.6 release notes

docs/docs/the-marten-project/release-notes/0.6.md

@@ -30,6 +30,7 @@ _Under development._
 * An alias for the [`#reverse`](pathname:///api/dev/Marten/Handlers/Base.html#reverse(*args%2C**options)-instance-method) handler method ([`#url`](pathname:///api/dev/Marten/Handlers/Base.html#url(name%3AString|Symbol%2C**kwargs)%3AString-instance-method)) was introduced.
 * A [Referrer-Policy middleware](../../handlers-and-http/reference/middlewares.md#referrer-policy-middleware) was introduced to make it possible to automatically set the Referrer-Policy header in responses generated by handlers.
 * A new [`unsupported_http_method_strategy`](../../development/reference/settings.md#unsupported_http_method_strategy) setting was introduced to make it possible to configure the strategy to use when processing unsupported HTTP methods in handlers. This setting can be used to configure whether such requests should result in 405 Method Not Allowed responses (the default behavior) or 404 Not Found responses.
+* It is now possible to use any hash or named tuple to define schema initial data in handlers that use subclasses of [`Marten::Handlers::Schema`](pathname:///api/dev/Marten/Handlers/Schema.html) (in the [`#initial_data`](pathname:///api/dev/Marten/Handlers/Schema.html#initial_data-instance-method) method).
 
 #### Templates