Fill in release date for 2.15.3

CHANGELOG.txt

@@ -58,7 +58,7 @@ Changelog
  * Fix: Ensure that programmatic page moves are correctly logged as 'move' and not 'reorder' in some cases (Andy Babic)
 
 
-2.15.3 (xx.xx.xxxx) - IN DEVELOPMENT
+2.15.3 (26.01.2022)
 ~~~~~~~~~~~~~~~~~~~
 
  * Fix: Implement correct check for SQLite installations without full-text search support (Matt Westcott)

docs/releases/2.15.3.rst

@@ -1,6 +1,6 @@
-=============================================
-Wagtail 2.15.3 release notes - IN DEVELOPMENT
-=============================================
+============================
+Wagtail 2.15.3 release notes
+============================
 
 .. contents::
     :local: