ch10: coinbase -> coinbase data

ch10.asciidoc

@@ -1046,7 +1046,7 @@ Irreversible upgrades:: Because soft forks create transactions with additional c
 
 ((("bitcoin improvement proposals", "Block v2, Height in Coinbase (BIP-34)")))The first implementation, in BIP-34, used the block version field to allow miners to signal readiness for a specific consensus rule change. Prior to BIP-34, the block version was set to "1" by _convention_ not enforced by _consensus_.
 
-BIP-34 defined a consensus rule change that required the coinbase field (input) of the coinbase transaction to contain the block height. Prior to BIP-34, the coinbase could contain any arbitrary data the miners chose to include. After activation of BIP-34, valid blocks had to contain a specific block-height at the beginning of the coinbase and be identified with a version number greater than or equal to "2."
+BIP-34 defined a consensus rule change that required the coinbase data field of a coinbase transaction input to contain the block height. Prior to BIP-34, the coinbase data could contain any arbitrary data the miners chose to include. After activation of BIP-34, valid blocks had to contain a specific block-height at the beginning of the coinbase data and be identified with a version number greater than or equal to "2."
 
 To signal the change and activation of BIP-34, miners set the block version to "2," instead of "1." This did not immediately make version "1" blocks invalid. Once activated, version "1" blocks would become invalid and all version "2" blocks would be required to contain the block height in the coinbase to be valid.