fix: correct link to trademark

Signed-off-by: Andy Scherzinger <info@andy-scherzinger.de>

LICENSES/LicenseRef-NextcloudTrademarks.txt

@@ -6,4 +6,4 @@ and our products: “Nextcloud Files”; “Nextcloud Groupware” and “Nextcl
 This set of marks is collectively referred to as the “Nextcloud marks.”
 
 Use of Nextcloud logos and other marks is only permitted under the guidelines provided by the Nextcloud GmbH.
-A copy can be found at https://discord.com/branding
+A copy can be found at https://nextcloud.com/trademarks/