Adding more usage details to the transporter tool.

BUG=None
Test=Manually

Change-Id: I7ea7b7faac6911c0e63e39af3138b32391f155be
Reviewed-on: https://chromium-review.googlesource.com/176713
Reviewed-by: Katherine Threlkeld <kathrelkeld@chromium.org>
Reviewed-by: Rohit Makasana <rohitbm@chromium.org>
Commit-Queue: Rohit Makasana <rohitbm@chromium.org>
Tested-by: Rohit Makasana <rohitbm@chromium.org>
diff --git a/provingground/transporter.py b/provingground/transporter.py
index e935eeb..90832c9 100755
--- a/provingground/transporter.py
+++ b/provingground/transporter.py
@@ -10,7 +10,9 @@
 
 def main():
   gs_path = 'gs://chromiumos-test-logs/'
-  parser = argparse.ArgumentParser()
+  usage_desc = ('Please make sure you are part of chromiumos-test-logs-ninja '
+                'group. Ping rohitbm/krisr to get yourself added to the group.') 
+  parser = argparse.ArgumentParser(description=usage_desc)
   parser.add_argument('-t', '--tracker', dest='tracker',
                       help='[crosp|cr|misc] bug\'s tracker name.')
   parser.add_argument('-b', '--bug', dest='bug_id',