code: func (c *Client) loadServerCert(cert string) error {
  	certPool := x509.NewCertPool()
  
  	asn1, err := base64.RawStdEncoding.DecodeString(cert)
  	if err != nil {
  		return err
  	}
  
  	x509Cert, err := x509.ParseCertificate([]byte(asn1))
  	if err != nil {
  		return err
  	}
  
  	certPool.AddCert(x509Cert)
  
  	c.config.TLSConfig.RootCAs = certPool
  	return nil
  }
docs: // loadServerCert is used by AutoMTLS to read an x.509 cert returned by the
  // server, and load it as the RootCA for the client TLSConfig.