clarify config comments about listunspent_args

caught by @AdamISZ

joinmarket/configure.py

@@ -138,15 +138,16 @@ def jm_single():
 # the range of confirmations passed to the `listunspent` bitcoind RPC call
 # 1st value is the inclusive minimum, defaults to one confirmation
 # 2nd value is the exclusive maximum, defaults to most-positive-bignum (Google Me!)
-# leave it unset to defer to bitcoind's default values, ie [1, 9999999]
-#listunspent = []
-# unless you have a specific reason, eg:
+# leaving it unset or empty defers to bitcoind's default values, ie [1, 9999999]
+#listunspent_args = []
+# that's what you should do, unless you have a specific reason, eg:
 #  spend from unconfirmed transactions:  listunspent_args = [0]
 # display only unconfirmed transactions: listunspent_args = [0, 1]
 # defend against small reorganizations:  listunspent_args = [3]
 #   who is at risk of reorganization?:   listunspent_args = [0, 2]
 # NB: using 0 for the 1st value with scripts other than wallet-tool could cause
 # spends from unconfirmed inputs, which may then get malleated or double-spent!
+# other counterparties are likely to reject unconfirmed inputs... don't do it.
 """