rpc: Properly document submitblock return value

Can be reviewed with --ignore-all-space

src/rpc/mining.cpp

@@ -947,7 +947,10 @@ static RPCHelpMan submitblock()
             {"hexdata", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "the hex-encoded block data to submit"},
             {"dummy", RPCArg::Type::STR, /* default */ "ignored", "dummy value, for compatibility with BIP22. This value is ignored."},
         },
-                RPCResult{RPCResult::Type::NONE, "", "Returns JSON Null when valid, a string according to BIP22 otherwise"},
+        {
+            RPCResult{"If the block was accepted", RPCResult::Type::NONE, "", ""},
+            RPCResult{"Otherwise", RPCResult::Type::STR, "", "According to BIP22"},
+        },
         RPCExamples{
                     HelpExampleCli("submitblock", "\"mydata\"")
             + HelpExampleRpc("submitblock", "\"mydata\"")