Add 6.3.1 release notes

CHANGELOG.txt

@@ -1,6 +1,12 @@
 Changelog
 =========
 
+6.3.1 (xx.xx.20xx) - IN DEVELOPMENT
+~~~~~~~~~~~~~~~~~~
+
+ * ...
+
+
 6.3 LTS (01.11.2024)
 ~~~~~~~~~~~~~~~~~~~~
 

docs/releases/6.3.1.md

@@ -0,0 +1,17 @@
+# Wagtail 6.3.1 release notes - IN DEVELOPMENT
+
+_Unreleased_
+
+```{contents}
+---
+local:
+depth: 1
+---
+```
+
+## What's new
+
+
+### Bug fixes
+
+ * ...

docs/releases/index.rst

@@ -5,6 +5,7 @@ Release notes
    :maxdepth: 1
 
    upgrading
+   6.3.1
    6.3
    6.2.3
    6.2.2