message: Update i18n for Appearance User Settings
  The variable has to be added to the i18n files as well (I don't know how to do that)
diff: @@ -394,7 +394,7 @@ export default class AppearanceUserSettingsTab extends React.Component<IProps, I
  className="mx_AppearanceUserSettingsTab_AdvancedToggle"
  onClick={() => this.setState({showAdvanced: !this.state.showAdvanced})}
  >
  - {this.state.showAdvanced ? "Hide advanced" : "Show advanced"}
  + {this.state.showAdvanced ? _t("Hide advanced") : _t("Show advanced")}
  </div>;
  let advanced: React.ReactNode;
  