Fill in release date for 3.0

CHANGELOG.txt

@@ -18,7 +18,7 @@ Changelog
  * Fix: Remove extra padding for headers with breadcrumbs on mobile viewport (Steven Steinwand)
 
 
-3.0 (xx.xx.xxxx) - IN DEVELOPMENT
+3.0 (16.05.2022)
 ~~~~~~~~~~~~~~~~
 
  * Phase out special-purpose panel types (`StreamFieldPanel`, `RichTextFieldPanel`, `ImageChooserPanel`, `DocumentChooserPanel`, `PageChooserPanel`, `SnippetChooserPanel`) in favour of `FieldPanel` (Matt Westcott)

docs/releases/3.0.md

@@ -1,4 +1,4 @@
-# Wagtail 3.0 release notes - IN DEVELOPMENT
+# Wagtail 3.0 release notes
 
 ```{contents}
 ---