ktest: Add documentation of CLOSE_CONSOLE_SIGNAL

The sample.conf file needs to document all available options.
With the new CLOSE_CONSOE_SIGNAL option, it too needs to be
document.

Cc: Satoru Takeuchi <satoru.takeuchi@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

tools/testing/ktest/sample.conf

@@ -328,6 +328,13 @@
 # For a virtual machine with guest name "Guest".
 #CONSOLE =  virsh console Guest
 
+# Signal to send to kill console.
+# ktest.pl will create a child process to monitor the console.
+# When the console is finished, ktest will kill the child process
+# with this signal.
+# (default INT)
+#CLOSE_CONSOLE_SIGNAL = HUP
+
 # Required version ending to differentiate the test
 # from other linux builds on the system.
 #LOCALVERSION = -test