code: protected function registerMarkdownParser()
      {
          $app = $this->app;
  
          $app->singleton('commonmark.docparser', function ($app) {
              $environment = $app['commonmark.environment'];
  
              return new DocParser($environment);
          });
  
          $app->alias('commonmark.docparser', DocParser::class);
      }
docs: Register the CommonMark DocParser.
  
  @return void