Merge pull request #11329 from nextcloud/backport/11328/stable28

[stable28] docs: remove to be documented

Author: ChristophWurst

admin_manual/release_notes/upgrade_to_28.rst

@@ -7,7 +7,6 @@ System requirements
 
 * PHP 8.3 is now supported, but 8.2 is recommended.
 
-To be documented
 
 Web server configuration
 ------------------------