clarify coinbase_tx_prefix and coinbase_tx_suffix field descriptions

these description fields were changed via 9b0e40b and it's an obvious mistake

Author: plebhash

06-Job-Declaration-Protocol.md

@@ -140,8 +140,8 @@ A request sent by JDC that proposes a selected set of transactions to JDS.
 | mining_job_token            | B0_255                | Previously reserved mining job token received by AllocateMiningJobToken.Success                                                                                                                                                                                                                                                                                                                                              |
 | version                     | U32                   | Version header field. To be later modified by BIP320-consistent changes.                                                                                                                                                                                                                                                                                                                                                     |
 | prev_hash                   | U256                  | Optional. Contains the chain tip that the template is based on. JDS SHOULD accept templates based on different tips, as long as they are on the best block height and don't contain double spends.                                                                                                                                                                                                                           |
-| coinbase_tx_prefix         | B0_64K                 | The coinbase transaction nVersion field                                                                                                                                                                                                                                                                                                                                                                                       |
-| coinbase_tx_suffix         | B0_64K                 | Up to 8 bytes (not including the length byte) which are to be placed at the beginning of the coinbase field in the coinbase transaction                                                                                                                                                                                                                                                                                      |
+| coinbase_tx_prefix         | B0_64K                 | Serialized bytes representing the initial part of the coinbase transaction (not including extranonce)                                                                                                                                                                                                                                                                                                                                                                                      |
+| coinbase_tx_suffix         | B0_64K                 | Serialized bytes representing the final part of the coinbase transaction (after extranonce)                                                                                                                                                                                                                                                                                     |
 | tx_ids_list               | SEQ0_64K[U256] | List of hashes of the transaction set contained in the template. JDS checks the list against its mempool and requests missing txs via `ProvideMissingTransactions`. Does not include the coinbase transaction (as there is no corresponding full data for it yet).                                                                                                                                                          |
 | excess_data                 | B0_64K                | Extra data which the Pool may require to validate the work (as defined in the Template Distribution Protocol)                                                                                                                                                                                                                                                                                                                |