add comments

src/apprt/gtk/App.zig

@@ -148,6 +148,7 @@ pub fn init(core_app: *CoreApp, opts: Options) !App {
         @"gles-api": bool = false,
         /// current gtk implementation for color management is not good enough.
         /// see: https://bugs.kde.org/show_bug.cgi?id=495647
+        /// gtk issue: https://gitlab.gnome.org/GNOME/gtk/-/issues/6864
         @"color-mgmt": bool = true,
         /// Disabling Vulkan can improve startup times by hundreds of
         /// milliseconds on some systems. We don't use Vulkan so we can just