config: make log rotation configurable

sample-lnd.conf

@@ -12,6 +12,12 @@
 ; Rotated logs are compressed in place.
 ; logdir=~/.lnd/logs
 
+; Number of logfiles that the log rotation should keep. Setting it to 0 disables deletion of old log files.
+; maxlogfiles=3
+; 
+; Max log file size in MB before it is rotated.
+; maxlogfilesize=10
+
 ; Path to TLS certificate for lnd's RPC and REST services.
 ; tlscertpath=~/.lnd/tls.cert