Add 25.08 upgrade notes

Author: badlop

content/admin/upgrade/index.md

@@ -101,6 +101,7 @@ of the new ejabberd version if you need to update those tables yourself manually
 The corresponsing ugprade notes are available in the release notes of each release,
 and also available in the [Archive](../../archive/index.md) section:
 
+- [Upgrading from ejabberd 25.07 to 25.08](../../archive/25.08/upgrade.md)
 - [Upgrading from ejabberd 25.04 to 25.07](../../archive/25.07/upgrade.md)
 - [Upgrading from ejabberd 25.03 to 25.04](../../archive/25.04/upgrade.md)
 - [Upgrading from ejabberd 24.12 to 25.03](../../archive/25.03/upgrade.md)

content/archive/25.08/upgrade.md

@@ -0,0 +1,5 @@
+# Upgrade to ejabberd 25.08
+
+If you upgrade ejabberd from a previous release to [25.08](../../archive/25.08/index.md),
+there are no changes in the configuration, SQL database, API, or hooks that require your attention
+before upgrading.