Hide Open Settings in Mark As Read confirmation

Fixes issue 3804. After showing the note and quick link to Settings to
disable the Mark As Read confirmation once don't show it again.

iOS/MasterTimeline/MarkAsReadAlertController.swift

@@ -46,8 +46,11 @@ struct MarkAsReadAlertController {
 							  completion: @escaping (UIAlertAction) -> Void) -> UIAlertController where T: MarkAsReadAlertControllerSourceType  {
 
 
+		let hasShownAlertKey = "hasShownMarkAsReadAlert"
+		let hasShownAlert = UserDefaults.standard.bool(forKey: hasShownAlertKey)
+
 		let title = NSLocalizedString("Mark As Read", comment: "Mark As Read")
-		let message = NSLocalizedString("You can turn this confirmation off in Settings.",
+		let message = hasShownAlert ? nil : NSLocalizedString("You can turn this confirmation off in Settings.",
 										comment: "You can turn this confirmation off in Settings.")
 		let cancelTitle = NSLocalizedString("Cancel", comment: "Cancel")
 		let settingsTitle = NSLocalizedString("Open Settings", comment: "Open Settings")
@@ -56,13 +59,16 @@ struct MarkAsReadAlertController {
 		let cancelAction = UIAlertAction(title: cancelTitle, style: .cancel) { _ in
 			cancelCompletion?()
 		}
-		let settingsAction = UIAlertAction(title: settingsTitle, style: .default) { _ in
-			coordinator.showSettings(scrollToArticlesSection: true)
-		}
 		let markAction = UIAlertAction(title: confirmTitle, style: .default, handler: completion)
 
 		alertController.addAction(markAction)
-		alertController.addAction(settingsAction)
+		if (!hasShownAlert) {
+			let settingsAction = UIAlertAction(title: settingsTitle, style: .default) { _ in
+				coordinator.showSettings(scrollToArticlesSection: true)
+			}
+			alertController.addAction(settingsAction)
+			UserDefaults.standard.set(true, forKey: hasShownAlertKey)
+		}
 		alertController.addAction(cancelAction)
 
 		if let barButtonItem = sourceType as? UIBarButtonItem {