lnd+rpcserver: allow customized timeout in ConnectPeer

sample-lnd.conf

@@ -158,6 +158,9 @@
 ; support devices behind multiple NATs.
 ; nat=true
 
+; The timeout value for network connections in seconds, default to 120 seconds.
+; Valid uints are {ms, s, m, h}.
+; connectiontimeout=120s
 
 ; Debug logging level.
 ; Valid levels are {trace, debug, info, warn, error, critical}