ktest: Comment about other names than just ktest.conf

ktest.pl will read any file as long as its name is specified as the first
argument on the command line. Comment this fact in sample.conf.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tools/testing/ktest/sample.conf

 #
 # Config file for ktest.pl
 #
-# Place your customized version of this, named ktest.conf, in the
-# working directory that ktest.pl is run from.
+# Place your customized version of this, in the working directory that
+# ktest.pl is run from. By default, ktest.pl will look for a file
+# called "ktest.conf", but you can name it anything you like and specify
+# the name of your config file as the first argument of ktest.pl.
 #
 # Note, all paths must be absolute
 #