bip-0054: add a reference implementation section

Author: darosior

bip-0054.md

@@ -154,6 +154,10 @@ knowledge, there does not exist an open source reference broadly in use today fo
 We encourage mining pools to update their software to craft coinbase transactions that are
 forward-compatible with the changes proposed in this BIP.
 
+## Reference implementation
+
+An implementation of BIP54 for Bitcoin Core is available [here][inquisition-implem].
+
 ## Acknowledgements
 
 This document builds upon an [earlier proposal][BIP-XXXX] by Matt Corallo.
@@ -232,3 +236,4 @@ notably of Bitcoin Core but also of all other implementations the authors are aw
 [Delving duplicable]: https://delvingbitcoin.org/t/great-consensus-cleanup-revival/710/4
 [Core 0.16.1]: https://bitcoincore.org/en/releases/0.16.1
 [Core 29.0]: https://bitcoincore.org/en/releases/29.0
+[inquisition-implem]: https://github.com/darosior/bitcoin/tree/2509_inquisition_consensus_cleanup