Fill in release date for 2.13.5

CHANGELOG.txt

@@ -128,7 +128,7 @@ Changelog
  * Fix: Ensure that rich text conversion correctly handles images / embeds inside links or inline styles (Matt Westcott)
 
 
-2.13.5 (xx.xx.xxxx) - IN DEVELOPMENT
+2.13.5 (14.10.2021)
 ~~~~~~~~~~~~~~~~~~~
 
  * Fix: Allow relation name used for admin commenting to be overridden to avoid conflicts with third-party commenting apps (Matt Westcott)

docs/releases/2.13.5.rst

@@ -1,6 +1,6 @@
-=============================================
-Wagtail 2.13.5 release notes - IN DEVELOPMENT
-=============================================
+============================
+Wagtail 2.13.5 release notes
+============================
 
 .. contents::
     :local: