doc: list support for BIP 339 in doc/bips.md

Author: sipa

doc/bips.md

@@ -1,4 +1,4 @@
-BIPs that are implemented by Bitcoin Core (up-to-date up to **v0.19.0**):
+BIPs that are implemented by Bitcoin Core (up-to-date up to **v0.21.0**):
 
 * [`BIP 9`](https://github.com/bitcoin/bips/blob/master/bip-0009.mediawiki): The changes allowing multiple soft-forks to be deployed in parallel have been implemented since **v0.12.1**  ([PR #7575](https://github.com/bitcoin/bitcoin/pull/7575))
 * [`BIP 11`](https://github.com/bitcoin/bips/blob/master/bip-0011.mediawiki): Multisig outputs are standard since **v0.6.0** ([PR #669](https://github.com/bitcoin/bitcoin/pull/669)).
@@ -42,3 +42,4 @@ BIPs that are implemented by Bitcoin Core (up-to-date up to **v0.19.0**):
 * [`BIP 173`](https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki): Bech32 addresses for native Segregated Witness outputs are supported as of **v0.16.0** ([PR 11167](https://github.com/bitcoin/bitcoin/pull/11167)). Bech32 addresses are generated by default as of **v0.20.0** ([PR 16884](https://github.com/bitcoin/bitcoin/pull/16884)).
 * [`BIP 174`](https://github.com/bitcoin/bips/blob/master/bip-0174.mediawiki): RPCs to operate on Partially Signed Bitcoin Transactions (PSBT) are present as of **v0.17.0** ([PR 13557](https://github.com/bitcoin/bitcoin/pull/13557)).
 * [`BIP 176`](https://github.com/bitcoin/bips/blob/master/bip-0176.mediawiki): Bits Denomination [QT only] is supported as of **v0.16.0** ([PR 12035](https://github.com/bitcoin/bitcoin/pull/12035)).
+* [`BIP 339`](https://github.com/bitcoin/bips/blob/master/bip-0339.mediawiki): Relay of transactions by wtxid is supported as of **v0.21.0** ([PR 18044](https://github.com/bitcoin/bitcoin/pull/18044)).