Merge #1560: rpc: fix fields description in a man in 'decodepsbt'

ef1d267 rpc: fix fields type in man in 'decodepsbt' (Ruslan Kasheparov)
91ae0e9 rpc: fix fields describtion in man in 'decodepsbt' (Ruslan Kasheparov)

Pull request description:

Top commit has no ACKs.

Tree-SHA512: 736f7ebfd3c54267aee8e7b25970a25356f9a4c38ac23caecd40a7f4b2a96c0142adc0e73bcbd6881243981297af2d5fcc68bae9023cca6179bee823d1dd9ecb

Author: tomt1664

src/rpc/rawtransaction.cpp

@@ -1153,11 +1153,9 @@ static RPCHelpMan decodepsbt()
                         {RPCResult::Type::NUM, "fees", "The fees specified in this psbt.", {}, /*skip_type_check=*/true}, // ELEMENTS has an explicit fee output, bitcoin does not (they are implicit)
                         {RPCResult::Type::NUM, "input_count", "The number of inputs in this psbt"},
                         {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, "inputs_modifiable", /*optional=*/true, "Whether inputs can be modified"},
+                        {RPCResult::Type::BOOL, "outputs_modifiable", /*optional=*/true, "Whether outputs can be modified"},
+                        {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",
                         {