Update 0.6 release notes

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

@@ -46,3 +46,4 @@ _Under development._
 * The [`new`](../../development/reference/management-commands.md#new) management command now generates a `seed.cr` file when generating new project structures.
 * A new [`seed`](../../development/reference/management-commands.md#seed) management command was introduced to make it easy to execute seed files.
 * Log entries generated when running the development server ([`serve`](../../development/reference/management-commands.md#serve) management command) in debug mode now include more details about processed requests, rendered templates, and executed SQL queries.
+* Database configuration now supports connection strings, which can be useful in scenarios where only a connection string is provided (e.g., via a `DATABASE_URL` environment variable from cloud providers). See [Database settings](../../development/reference/settings.md#database-settings) to learn more about this new capability.