docs: function ensureDockerVersion() {
      if (opts.generate) {
          return P.resolve(true);
      }
      return promisedSpawn(['docker', 'version', '--format', '{{.Server.Version}}'], {
          capture: true
      })
      .then((dockerVersion) => {
          if (!dockerVersion) {
              console.error('Docker is not found.');
              process.exit(1);
          }
  
          const minimumDockerVersion = os.type() === 'Darwin' ? '1.12.0' : '1.8.0';
          dockerVersion = dockerVersion.replace(/\.0+(0|[1-9]+)/g, '.$1');
          if (semver.lt(dockerVersion, minimumDockerVersion)) {
              console.error(`Building the deploy repo on ${os.type()} supported only with docker ${minimumDockerVersion}+`);
              process.exit(1);
          }
      });
  }