rpc: fix fields describtion in man in 'decodepsbt'

Author: RuslanProgrammer

src/rpc/rawtransaction.cpp

@@ -1155,9 +1155,7 @@ static RPCHelpMan decodepsbt()
                         {RPCResult::Type::NUM, "output_count", "The number of outputs in this psbt."},
                         {RPCResult::Type::NUM, "inputs_modifiable", /*optional=*/true, "Whether inputs can be modified"},
                         {RPCResult::Type::NUM, "outputs_modifiable", /*optional=*/true, "Whether outputs can be modified"},
-                        {RPCResult::Type::ARR, "sighash_single_indexes", /*optional=*/true, "The indexes which have SIGHASH_SINGLE signatures",
-                            {{RPCResult::Type::NUM, "", "Index of an input with a SIGHASH_SINGLE signature"}},
-                        },
+                        {RPCResult::Type::BOOL, "has_sighash_single", /*optional=*/true, "Whether this PSBT has SIGHASH_SINGLE inputs"},
                         {RPCResult::Type::NUM, "psbt_version", "The PSBT version number. Not to be confused with the unsigned transaction version"},
                         {RPCResult::Type::ARR, "scalar_offsets", /*optional=*/true, "The PSET scalar elements",
                         {