fix(nsqd): fix log_level on nsqd.cfg (#14)

Use log_level instead of log-level.

See: https://github.com/nsqio/nsq/blob/d0f7412f69a4b4ce6b13ff0dcd48cd42f616a67b/contrib/nsqd.cfg.example#L2

Author: monaka

rootfs/opt/nsq/conf/nsqd.cfg

@@ -1,5 +1,5 @@
 ## log verbosity level: debug, info, warn, error, or fatal
-log-level = "warn"
+log_level = "warn"
 verbose = false
 
 ## path to store disk-backed messages