corosync.conf.example: include comments

It's nice to say people should read the man page. It's also naive to
assume that they always do. Include comments in the example config
file itself.

Signed-off-by: Florian Haas <florian.haas@linbit.com>
Reviewed-by: Dan Frincu <dan.frincu@1and1.ro>
Reviewed-by: Jan Friesse <jfriesse@redhat.com>
Reviewed-by: Steven Dake <sdake@redhat.com>
(cherry picked from commit 6fa4a339b1562f608313c1a14cf9b63b0c4b9ec9)

conf/corosync.conf.example

@@ -3,24 +3,64 @@ compatibility: whitetank
 
 totem {
 	version: 2
+
+	# secauth: Enable mutual node authentication. If you choose to
+	# enable this ("on"), then do remember to create a shared
+	# secret with "corosync-keygen".
 	secauth: off
+
 	threads: 0
+
+	# interface: define at least one interface to communicate
+	# over. If you define more than one interface stanza, you must
+	# also set rrp_mode.
 	interface {
+                # Rings must be consecutively numbered, starting at 0.
 		ringnumber: 0
+		# This is the *network* address of the interface to
+		# bind to. This ensures that you can use identical
+		# instances of this configuration file across all your
+		# cluster nodes, without having to modify this option.
 		bindnetaddr: 192.168.1.0
+		# When selecting a multicast address, consider RFC
+		# 2365 (which, among other things, specifies that
+		# 239.255.x.x addresses are left to the discretion of
+		# the network administrator). Do not reuse multicast
+		# addresses across multiple Corosync clusters sharing
+		# the same network.
 		mcastaddr: 239.255.1.1
+		# Corosync uses the port you specify here for UDP
+		# messaging, and also the immediately preceding
+		# port. Thus if you set this to 5405, Corosync sends
+		# messages over UDP ports 5405 and 5404.
 		mcastport: 5405
+		# Time-to-live for cluster communication packets. The
+		# number of hops (routers) that this ring will allow
+		# itself to pass. Note that multicast routing must be
+		# specifically enabled on most network routers.
 		ttl: 1
 	}
 }
 
 logging {
+	# Log the source file and line where messages are being
+	# generated. When in doubt, leave off. Potentially useful for
+	# debugging.
 	fileline: off
+	# Log to standard error. When in doubt, set to no. Useful when
+	# running in the foreground (when invoking "corosync -f")
 	to_stderr: no
+	# Log to a log file. When set to "no", the "logfile" option
+	# must not be set.
 	to_logfile: yes
-	to_syslog: yes
 	logfile: /var/log/cluster/corosync.log
+	# Log to the system log daemon. When in doubt, set to yes.
+	to_syslog: yes
+	# Log debug messages (very verbose). When in doubt, leave off.
 	debug: off
+	# Log messages with time stamps. When in doubt, set to on
+	# (unless you are only logging to syslog, where double
+	# timestamps can be annoying).
 	timestamp: on
 	logger_subsys {
 		subsys: AMF