List all commands, or get help for a specified command.
commandstringoptionalcurl --user myuser --data-binary '{"jsonrpc":"1.0","id":"1","method":"help","params":[]}' -H 'content-type:text/plain;' http://127.0.0.1:8332/"== Blockchain ==\ngetbestblockhash\ngetblock \"blockhash\" ( verbosity )\n..."