add cli example for walletcreatefundedpsbt and createpsbt RPCs
The only example present earlier was one that creates an OP_RETURN output. This lack of examples has discouraged me earlier to use this RPC. Adding an example that creates PSBT sending bitcoin to address, a scenario that is much more common.
rpc: update the doc for data field in outputs argument
It was not evident to me that this field creates an OP_RETURN output until
I read the code and tried it out. Thus, making the doc explicitly mention it.
This affects docs of the following RPCs:
bumpfee, psbtbumpfee, send, walletcreatefundedpsbt, createpsbt,
and createrawtransaction