a2a92317ad4ab88cfca234f68337a7cd37897f10 rpc: Add warning to user about newkeypool command (Samuel Dobson)
Pull request description:
This PR prevents `newkeypool` from being run on non-HD wallets, because this would require a new backup every time, so it isn't very safe.
David Harding also suggested [here](https://github.com/bitcoin/bitcoin/pull/23093#issuecomment-945350003) that the RPC help text should include a warning to the users about the interaction between newkeypool.
ACKs for top commit:
achow101:
ACK a2a92317ad4ab88cfca234f68337a7cd37897f10
Tree-SHA512: 0aa497900f1d179764bce13ffce0bb081ba2ca354492bf2e04b21d0212e960b3ed13a386fbf65602b6b50461f4056a0285752ef707d312da28e82449cd8ea048