[wallet] Clarify getbalance help string to explain interaction with bumpfee

Documentation change only, no change in behavior.

src/wallet/rpcwallet.cpp

@@ -668,7 +668,18 @@ UniValue getbalance(const JSONRPCRequest& request)
             "Note that the account \"\" is not the same as leaving the parameter out.\n"
             "The server total may be different to the balance in the default \"\" account.\n"
             "\nArguments:\n"
-            "1. \"account\"      (string, optional) DEPRECATED. The selected account, or \"*\" for entire wallet. It may be the default account using \"\".\n"
+            "1. \"account\"         (string, optional) DEPRECATED. The account string may be given as a\n"
+            "                     specific account name to find the balance associated with wallet keys in\n"
+            "                     a named account, or as the empty string (\"\") to find the balance\n"
+            "                     associated with wallet keys not in any named account, or as \"*\" to find\n"
+            "                     the balance associated with all wallet keys regardless of account.\n"
+            "                     When this option is specified, it calculates the balance in a different\n"
+            "                     way than when it is not specified, and which can count spends twice when\n"
+            "                     there are conflicting pending transactions (such as those created by\n"
+            "                     the bumpfee command), temporarily resulting in low or even negative\n"
+            "                     balances. In general, account balance calculation is not considered\n"
+            "                     reliable and has resulted in confusing outcomes, so it is recommended to\n"
+            "                     avoid passing this argument.\n"
             "2. minconf           (numeric, optional, default=1) Only include transactions confirmed at least this many times.\n"
             "3. include_watchonly (bool, optional, default=false) Also include balance in watch-only addresses (see 'importaddress')\n"
             "\nResult:\n"
@@ -696,9 +707,12 @@ UniValue getbalance(const JSONRPCRequest& request)
             filter = filter | ISMINE_WATCH_ONLY;
 
     if (request.params[0].get_str() == "*") {
-        // Calculate total balance a different way from GetBalance()
-        // (GetBalance() sums up all unspent TxOuts)
-        // getbalance and "getbalance * 1 true" should return the same number
+        // Calculate total balance in a very different way from GetBalance().
+        // The biggest difference is that GetBalance() sums up all unspent
+        // TxOuts paying to the wallet, while this sums up both spent and
+        // unspent TxOuts paying to the wallet, and then subtracts the values of
+        // TxIns spending from the wallet. This also has fewer restrictions on
+        // which unconfirmed transactions are considered trusted.
         CAmount nBalance = 0;
         for (map<uint256, CWalletTx>::iterator it = pwalletMain->mapWallet.begin(); it != pwalletMain->mapWallet.end(); ++it)
         {