update plugin repo url

Author: jjw24

Flow.Launcher/ViewModel/SettingWindowViewModel.cs

@@ -213,7 +213,7 @@ public string TestProxy()
 
         #region plugin
 
-        public static string Plugin => "http://www.wox.one/plugin";
+        public static string Plugin => @"https://github.com/Flow-Launcher/Flow.Launcher.PluginsManifest";
         public PluginViewModel SelectedPlugin { get; set; }
 
         public IList<PluginViewModel> PluginViewModels