Merge #14811: Mining: Enforce that segwit option must be set in GBT

d2ce315fbf [docs] add release note for change to GBT (John Newbery)
0025c9eae4 [mining] segwit option must be set in GBT (John Newbery)

Pull request description:

  Calling getblocktemplate without the segwit rule specified is most
  likely a client error, since it results in lower fees for the miner.
  Prevent this client error by failing getblocktemplate if called without
  the segwit rule specified.

  Of the previous 1000 blocks (measured at block [551591 (hash 0x...173c811)](https://blockstream.info/block/000000000000000000173c811e79858808abc3216af607035973f002bef60a7a)), 991 included segwit transactions.

Tree-SHA512: 7933b073d72683c9ab9318db46a085ec19a56a14937945c73f783ac7656887619a86b74db0bdfcb8121df44f63a1d6a6fb19e98505b2a26a6a8a6e768e442fee

doc/release-notes.md

@@ -65,6 +65,13 @@ platform.
 Notable changes
 ===============
 
+Mining
+------
+
+- Calls to `getblocktemplate` will fail if the segwit rule is not specified.
+  Calling `getblocktemplate` without segwit specified is almost certainly
+  a misconfiguration since doing so results in lower rewards for the miner.
+
 Command line option changes
 ---------------------------
 
@@ -182,6 +189,8 @@ in the Low-level Changes section below.
   P2SH-P2WPKH, and P2SH-P2WSH. Requests for P2WSH and P2SH-P2WSH accept
   an additional `witnessscript` parameter.
 
+- See the [Mining](#mining) section for changes to `getblocktemplate`.
+
 Low-level changes
 =================