code: func (c *Credentials) Create(ctx context.Context, creds []envelope.CredentialInf) ([]*envelope.Credential, error) {
  	resp := []*envelope.Credential{}
  	err := c.client.RoundTrip(ctx, "POST", "/credentials", nil, creds, &resp)
  	return resp, err
  }
docs: // Create creates the provided credential in the registry.