message: rename to `purse_identifier`
diff: @@ -125,7 +125,7 @@ static QUERY_BALANCE_PARAMS: Lazy<QueryBalanceParams> = Lazy::new(|| QueryBalanc
  state_identifier: Some(GlobalStateIdentifier::BlockHash(
  *Block::doc_example().hash(),
  )),
  - balance_identifier: PurseIdentifier::MainPurseUnderAccountHash(AccountHash::new([9u8; 32])),
  + purse_identifier: PurseIdentifier::MainPurseUnderAccountHash(AccountHash::new([9u8; 32])),
  });
  static QUERY_BALANCE_RESULT: Lazy<QueryBalanceResult> = Lazy::new(|| QueryBalanceResult {
  api_version: DOCS_EXAMPLE_PROTOCOL_VERSION,
  @@ -947,7 +947,7 @@ pub struct QueryBalanceParams {
  /// The state identifier used for the query.
  pub state_identifier: Option<GlobalStateIdentifier>,
  /// The identifier to obtain the purse corresponding to balance query.
  - pub balance_identifier: PurseIdentifier,
  + pub purse_identifier: PurseIdentifier,
  }
  impl DocExample for QueryBalanceParams {
  @@ -1014,7 +1014,7 @@ impl RpcWithParamsExt for QueryBalance {
  }
  };
  - let purse_uref = match params.balance_identifier {
  + let purse_uref = match params.purse_identifier {
  PurseIdentifier::MainPurseUnderPublicKey(account_public_key) => {
  match get_account(
  effect_builder,
  