addSection_(name, docLink) {
    const style = name ?
                  shakaDemo.InputContainer.Style.ACCORDION :
                  shakaDemo.InputContainer.Style.VERTICAL;
    this.sections_.push(new shakaDemo.InputContainer(
        this.container_, name, style, docLink));

    return this;
  }
@param {?string} name
@param {?string} docLink
@return {!shakaDemo.Config}
@private