change address preferred providers

iOSClient/Brand/NCBrand.swift

@@ -73,7 +73,7 @@ class NCBrandColor: NSObject {
     @objc public let textCopyrightNextcloudiOS:         String = "Nextcloud for iOS %@ © 2018 T.W.S. Inc."
     @objc public let textCopyrightNextcloudServer:      String = "Nextcloud Server %@"
     @objc public let loginBaseUrl:                      String = "https://cloud.twsweb.it"
-    @objc public let loginPreferredProviders:           String = "https://nextcloud.com/register";
+    @objc public let loginPreferredProviders:           String = "https://nextcloud.com/signup";
     @objc public let pushNotificationServerProxy:       String = "https://push-notifications.nextcloud.com"
     @objc public let linkLoginProvider:                 String = "https://nextcloud.com/providers"
     @objc public let textLoginProvider:                 String = "_login_bottom_label_"