[docs] max sections deprecation

Author: ferranrecio

docs/devupdate.md

@@ -8,3 +8,10 @@ tags:
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 This page highlights the important changes that are coming in Moodle 5.1 for developers.
+
+## Course format: max sections setting is now deprecated
+
+<Since version="5.1" issueNumber="MDL-84291" />
+The `maxsections` setting in course formats is now deprecated. Previously, this setting was used to limit the number of sections in a course. Starting with Moodle 5.1, courses can have an unlimited number of sections.
+
+Although the `maxsections` setting remains available for now, it is marked as deprecated and will be removed in Moodle 6.0. If your format plugin depends on `maxsections`, you should implement a custom setting within your plugin to manage section limits.