Clarify getbalance meaning a tiny bit in response to questions.

src/wallet/rpcwallet.cpp

@@ -771,6 +771,8 @@ UniValue getbalance(const JSONRPCRequest& request)
         throw std::runtime_error(
             "getbalance ( \"account\" minconf include_watchonly )\n"
             "\nIf account is not specified, returns the server's total available balance.\n"
+            "The available balance is what the wallet considers currently spendable, and is\n"
+            "thus affected by options which limit spendability such as -spendzeroconfchange.\n"
             "If account is specified (DEPRECATED), returns the balance in the account.\n"
             "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"