Adjust the help strings to better reflect usage

The default format is png (and not svg) so we should
note that instead of having svg mentioned (this was
leftover from the clone of this from taskflow which
does default to svg).

Change-Id: I108857ecc606ed2c12e0d5b460a8e72eb95af740

tools/states_to_dot.py

@@ -54,9 +54,9 @@ def format_state(state):
 def main():
     parser = optparse.OptionParser()
     parser.add_option("-f", "--file", dest="filename",
-                      help="write svg to FILE", metavar="FILE")
+                      help="write output to FILE", metavar="FILE")
     parser.add_option("-T", "--format", dest="format",
-                      help="output in given format",
+                      help="output in given format (default: png)",
                       default='png')
     parser.add_option("--no-labels", dest="labels",
                       help="do not include labels",