Added the "open" case to the Stack enumeration for the Browse module.

Modules/Sources/Browse/UI/Enumerations/Stack.swift

@@ -8,6 +8,7 @@
 
 enum Stack {
     case browse(Folder)
+    case open(Document)
 }
 
 // MARK: - Computed
@@ -16,6 +17,8 @@ extension Stack {
     var tag: String {
         if case .browse(let folder) = self {
             return folder.id
+        } else if case .open(let document) = self {
+            return document.id
         } else {
             return .Constants.noId
         }