Update the sample config file.

This commit adds a few more available options to the sample config file
and clarifies a few things.

sample-btcd.conf

@@ -20,7 +20,8 @@
 ; Use testnet.
 ; testnet=1
 
-; Connect via a SOCKS5 proxy.
+; Connect via a SOCKS5 proxy.  NOTE: Specifying a proxy without the 'tor' option
+; below will disable listening for incoming connections.
 ; proxy=127.0.0.1:9050
 ; proxyuser=
 ; proxypass=
@@ -34,18 +35,44 @@
 ;      feature of Tor to be used. 
 ; tor=1
 
+; ******************************************************************************
+; Only one of the following two options, 'addpeer' and 'connect', may be
+; specified.  Both allow you to specify peers that you want to stay connected
+; with, but the behavior is slightly different.  By default, btcd will query DNS
+; to find peers to connect to, so unless you have a specific reason such as
+; those described below, you probably won't need to modify anything here.
+;
+; 'addpeer' does not prevent connections to other peers discovered from
+; the peers you are connected to and also lets the remote peers know you are
+; available so they can notify other peers they can to connect to you.  This
+; option might be useful if you are having problems finding a node for some
+; reason (perhaps due to a firewall).
+;
+; 'connect', on the other hand, will ONLY connect to the specified peers and
+; no others.  It also disables listening and DNS seeding, so you will not be
+; advertised as an available peer to the peers you connect to and won't accept
+; connections from any other peers.  So, the 'connect' option effectively allows
+; you to only connect to "trusted" peers.
+; ******************************************************************************
 
 ; Add persistent peers to connect to as desired.  One peer per line.
 ; You may specify each IP address with or without a port.  The default port will
 ; be added automatically if one is not specified here.
-;
-; NOTE: btcd only currently works with a single peer, but this will be changing
-; soon as multi-peer support is under development.
 ; addpeer=192.168.1.1
 ; addpeer=10.0.0.2:8333
 ; addpeer=fe80::1
 ; addpeer=[fe80::2]:8333
 
+; Add persistent peers that you ONLY want to connect to as desired.  One peer
+; per line.  You may specify each IP address with or without a port.  The
+; default port will be added automatically if one is not specified here.
+; NOTE: Specifying this option will disable listening for incoming connections
+; and DNS seeding for peers.
+; connect=192.168.1.1
+; connect=10.0.0.2:8333
+; connect=fe80::1
+; connect=[fe80::2]:8333
+
 ; Maximum number of inbound and outbound peers.
 ; maxpeers=8
 
@@ -54,6 +81,13 @@
 ; banduration=24h
 ; banduration=11h30m15s
 
+; Disable DNS seeding for peers.  By default, when btcd starts, it will use
+; DNS to query for available peers to connect with.
+; nodnsseed=1
+
+; Disable listening for incoming connections.
+; nolisten=1
+
 
 ; ------------------------------------------------------------------------------
 ; RPC server options - The following options control the built-in RPC server