async generateFromURL(asyncapiURL) {
    const doc = await fetchSpec(asyncapiURL);
    return await this.generate(doc, { path: asyncapiURL });
  }
Generates files from a given template and AsyncAPI file stored on external server.

@example
generator
  .generateFromURL('https://example.com/asyncapi.yaml')
  .then(() => {
    console.log('Done!');
  })
  .catch(console.error);

@example <caption>Using async/await</caption>
try {
  await generator.generateFromURL('https://example.com/asyncapi.yaml');
  console.log('Done!');
} catch (e) {
  console.error(e);
}

@param  {String} asyncapiURL Link to AsyncAPI file
@return {Promise<TemplateRenderResult|undefined>}