rpc, wallet: Document mempool scan after importpubkey

Author: fjahr

src/wallet/rpc/backup.cpp

@@ -404,11 +404,13 @@ RPCHelpMan importpubkey()
                 "Hint: use importmulti to import more than one public key.\n"
             "\nNote: This call can take over an hour to complete if rescan is true, during that time, other rpc calls\n"
             "may report that the imported pubkey exists but related transactions are still missing, leading to temporarily incorrect/bogus balances and unspent outputs until rescan completes.\n"
+            "The rescan parameter can be set to false if the key was never used to create transactions. If it is set to false,\n"
+            "but the key was used to create transactions, rescanwallet needs to be called with the appropriate block range.\n"
             "Note: Use \"getwalletinfo\" to query the scanning progress.\n",
                 {
                     {"pubkey", RPCArg::Type::STR, RPCArg::Optional::NO, "The hex-encoded public key"},
                     {"label", RPCArg::Type::STR, RPCArg::Default{""}, "An optional label"},
-                    {"rescan", RPCArg::Type::BOOL, RPCArg::Default{true}, "Rescan the wallet for transactions"},
+                    {"rescan", RPCArg::Type::BOOL, RPCArg::Default{true}, "Scan the chain and mempool for wallet transactions."},
                 },
                 RPCResult{RPCResult::Type::NONE, "", ""},
                 RPCExamples{