Document deprecation of entity slugs

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

developer_manual/app_publishing_maintenance/app_upgrade_guide/upgrade_to_24.rst

@@ -18,9 +18,11 @@ Make sure your ``appinfo/info.xml`` allows for Nextcloud 24.
 	  <nextcloud min-version="21" max-version="24" />
 	</dependencies>
 
+Back-end changes
+----------------
 
 PHP8.1
-------
+^^^^^^
 
 Nextcloud 24 is the first major Nextcloud release to work with PHP8.1. Follow the steps below to make your app compatible.
 
@@ -47,3 +49,9 @@ Nextcloud 24 is the first major Nextcloud release to work with PHP8.1. Follow th
 3. If you have :ref:`continuous integration <app-ci>` set up, extend your test matrix with PHP8.1 tests and linters.
 
 Information about code changes can be found on `php.net <https://www.php.net/migration81>`__ and `stitcher.io <https://stitcher.io/blog/new-in-php-81#breaking-changes>`__.
+
+
+Entity slug deprecation
+^^^^^^^^^^^^^^^^^^^^^^^
+
+The usage of :ref:`entity slugs <database-entity-slugs>` has been deprecated. There is no provided replacement. If your app needs slugs, add your own logic to create them.

developer_manual/basics/storage/database.rst

@@ -312,9 +312,10 @@ mapping, simply override the **columnToProperty** and **propertyToColumn** metho
 
     }
 
+.. _database-entity-slugs:
 
-Slugs
-^^^^^
+Slugs (deprecated)
+^^^^^^^^^^^^^^^^^^
 
 Slugs are used to identify resources in the URL by a string rather than integer id. Since the URL allows only certain values, the entity base class provides a slugify method for it:
 
@@ -325,6 +326,8 @@ Slugs are used to identify resources in the URL by a string rather than integer
     $author->setName('Some*thing');
     $author->slugify('name');  // Some-thing
 
+.. note:: Entity slugs have been deprecated with the release of Nextcloud 24
+
 Table management tips
 -------------------------