**Is your feature request related to a problem? Please describe.**

MenuItem labels are meant to be short. There's currently no place to elaborate/clarify them.

**Describe the solution you'd like**

`NSMenuItem` supports a [`toolTip`](https://developer.apple.com/documentation/appkit/nsmenuitem/1514848-tooltip?language=objc) property. Would be nice if Electron could expose this.

From what I could find, [GTK (Linux) does not have any way to set tooltip on menu items](https://developer.gnome.org/gtk3/stable/GtkMenuItem.html).

No idea about Windows.

**Describe alternatives you've considered**

None.

**Additional context**

No.
shell/browser/api/atom_api_menu.cc
return model_->WorksWhenHiddenAt(index);
}
void Menu::OnMenuWillClose() {
  Emit("menu-will-close");
}
void Menu::OnMenuWillShow() {
  Emit("menu-will-show");
}
void Menu::BuildPrototype(v8::Isolate* isolate,
                          v8::Local<v8::FunctionTemplate> prototype) {
  prototype->SetClassName(mate::StringToV8(isolate, "Menu"));
  mate::ObjectTemplateBuilder(isolate, prototype->PrototypeTemplate())
      .MakeDestroyable()
      .SetMethod("insertItem", &Menu::InsertItemAt)
      .SetMethod("insertCheckItem", &Menu::InsertCheckItemAt)
      .SetMethod("insertRadioItem", &Menu::InsertRadioItemAt)
      .SetMethod("insertSeparator", &Menu::InsertSeparatorAt)
      .SetMethod("insertSubMenu", &Menu::InsertSubMenuAt)
      .SetMethod("setIcon", &Menu::SetIcon)
      .SetMethod("setSublabel", &Menu::SetSublabel)
      .SetMethod("setRole", &Menu::SetRole)
      .SetMethod("clear", &Menu::Clear)
      .SetMethod("getIndexOfCommandId", &Menu::GetIndexOfCommandId)
      .SetMethod("getItemCount", &Menu::GetItemCount)
      .SetMethod("getCommandIdAt", &Menu::GetCommandIdAt)
      .SetMethod("getLabelAt", &Menu::GetLabelAt)
      .SetMethod("getSublabelAt", &Menu::GetSublabelAt)
      .SetMethod("getAcceleratorTextAt", &Menu::GetAcceleratorTextAt)