Link to RFC 85 and mention modeladmin deprecation in future release

docs/reference/contrib/modeladmin/index.md

@@ -2,6 +2,10 @@
 
 The `modeladmin` module allows you to add any model in your project to the Wagtail admin. You can create customisable listing pages for a model, including plain Django models, and add navigation elements so that a model can be accessed directly from the Wagtail admin. Simply extend the `ModelAdmin` class, override a few attributes to suit your needs, register it with Wagtail using an easy one-line `modeladmin_register` method (you can copy and paste from the examples below), and you're good to go. Your model doesn’t need to extend `Page` or be registered as a `Snippet`, and it won’t interfere with any of the existing admin functionality that Wagtail provides.
 
+```{note}
+The `modeladmin` module will be deprecated in a future release and published as a separate package. We recommend using [](snippets) instead.
+```
+
 (modeladmin_feature_summary)=
 
 ## Summary of features

docs/releases/5.0.md

@@ -74,7 +74,7 @@ We hope this new theme will bring accessibility improvements for users who perfe
 
 ### Snippets parity with ModelAdmin
 
-Continuing on recent improvements to snippets, we have made the following improvements to how snippets can be customised in the admin interface:
+Continuing on recent improvements to snippets, we have made the following additions to how snippets can be customised in the admin interface:
 
  * Allow customising the base URL and URL namespace for snippet views.
  * Allow customising the default ordering and number of items per page for snippet listing views.
@@ -86,7 +86,9 @@ Continuing on recent improvements to snippets, we have made the following improv
  * Support for customising icons for snippets via `SnippetViewSet.icon`.
  * Allow snippets to be registered into arbitrary admin menu items.
 
-These features were developed by Sage Abdullah.
+For more details, see [](wagtailsnippets_custom_admin_views).
+
+Developed by Sage Abdullah, these features were implemented as part of [RFC 85: Snippets parity with ModelAdmin](https://github.com/wagtail/rfcs/pull/85). We will start the deprecation process of the ModelAdmin contrib package in the next feature release and publish it as a separate package for users who wish to continue using it. The ModelAdmin package will be removed in Wagtail 6.0.
 
 ### Other features