message: update function `from_era` to `from_bootstrap_era`
diff: @@ -372,9 +372,9 @@ pub struct Attributes {
  // attr_remains ? whatever...
  }
  impl Attributes {
  - pub fn new_era() -> Self {
  + pub fn new_bootstrap_era(hdap: Option<HDAddressPayload>) -> Self {
  Attributes {
  - derivation_path: None,
  + derivation_path: hdap,
  stake_distribution: StakeDistribution::BootstrapEraDistr
  }
  }
  @@ -669,7 +669,7 @@ mod tests {
  use hdwallet;
  let sk = hdwallet::generate(&[0;hdwallet::SEED_SIZE]);
  let pk = hdwallet::to_public(&sk);
  - let sd_1 = StakeDistribution::new_era();
  + let sd_1 = StakeDistribution::new_bootstrap_era(None);
  let sd_2 = StakeDistribution::new_single_key(&pk);
  assert!(hs_cbor::encode_decode(&sd_1));
  assert!(hs_cbor::encode_decode(&sd_2));
  