fix string

iOSClient/Supporting Files/en.lproj/Localizable.strings

@@ -609,7 +609,7 @@
 
 // Offline
 
-"_manage_file_offline_"             = "Manage file Offline";
+"_manage_file_offline_"             = "Manage file offline";
 "_set_available_offline_"           = "Set as available offline";
 "_remove_available_offline_"        = "Remove as available offline";