Merge #16845: test: Add notes on how to generate data/wallets/high_minversion

2222c96 test: Add notes on how to generate data/wallets/high_minversion (MarcoFalke)

Pull request description:

  I forgot to do this in #16796

ACKs for top commit:
  ryanofsky:
    ACK 2222c96

Tree-SHA512: 5f24ffa641b97eac4febad42ade7228b14fa72335c918a10880c5dec86a3ecc3075a31526f275188e07fea95b8e2c6320c64f716099f604b00e13d5366fcee37

Author: MarcoFalke

test/functional/data/wallets/high_minversion/GENERATE.md

@@ -0,0 +1,8 @@
+The wallet has been created by starting Bitcoin Core with the options
+`-regtest -datadir=/tmp -nowallet -walletdir=$(pwd)/test/functional/data/wallets/`.
+
+In the source code, `WalletFeature::FEATURE_LATEST` has been modified to be large, so that the minversion is too high
+for a current build of the wallet.
+
+The wallet has then been created with the RPC `createwallet high_minversion true true`, so that a blank wallet with
+private keys disabled is created.