fix(replaycons): print full usage on missing argument, document confluent log rotation

When invoked with no node name, replaycons printed a terse "Please specify a
node name."  Print the full usage statement instead, consistent with -h.

Also document, in the man page, that confluent log rotation renames older logs
and how to replay one by appending the date suffix seen in
/var/log/confluent/consoles/.

Recovered from the unmerged lenovobuild branch (originals 1c1b23fac, 48a92b7d4).

Co-authored-by: Jarrod Johnson <10814490+jjohnson42@users.noreply.github.com>

docs/source/guides/admin-guides/references/man1/replaycons.1.rst

@@ -36,6 +36,10 @@ the speed of the output play back.  (The logs are stored in /var/log/consoles.)
 \ **replaycons**\  must be run locally on the system on which the console log is stored.  This is normally
 that management node, but in a hierarchical cluster will usually be the service node.
 
+Note that when used with confluent, log rotation will cause older logs to have a filename that replaycons
+does not understand.  You can have replaycons process an older log by appending the suffix seen in
+/var/log/confluent/consoles/.  For example, 'replaycons n1.2018-02-02' will show the log file indicated.
+
 
 *******
 OPTIONS

xCAT-client/pods/man1/replaycons.1.pod

@@ -19,6 +19,10 @@ the speed of the output play back.  (The logs are stored in /var/log/consoles.)
 B<replaycons> must be run locally on the system on which the console log is stored.  This is normally
 that management node, but in a hierarchical cluster will usually be the service node.
 
+Note that when used with confluent, log rotation will cause older logs to have a filename that replaycons
+does not understand.  You can have replaycons process an older log by appending the suffix seen in
+/var/log/confluent/consoles/.  For example, 'replaycons n1.2018-02-02' will show the log file indicated.
+
 
 =head1 OPTIONS
 

xCAT-server/bin/replaycons

@@ -45,7 +45,7 @@ if ($::VERSION) {
 }
 
 if (@ARGV < 1) {
-    print "Please specify a node name.\n";
+    print "$usage_string\n";
     exit(1);
 }