Estimates the approximate fee per kilobyte needed for a transaction to begin confirmation within conf_target blocks.
conf_targetnumberREQUIREDestimate_modestringoptionalcurl --user myuser --data-binary '{"jsonrpc":"1.0","id":"1","method":"estimatesmartfee","params":[6]}' -H 'content-type:text/plain;' http://127.0.0.1:8332/{
"feerate": 0.00012345,
"blocks": 6
}