correct image_to_vm option description

Functionality changed at some point but description did not.

BUG=None
TEST=ran script and it worked according to new description

Change-Id: Ie16245b87389427420334bf1d0c78ccc68dd5091
Reviewed-on: https://chromium-review.googlesource.com/1140953
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Jacob Kopczynski <jkop@chromium.org>
Reviewed-by: Jacob Kopczynski <jkop@chromium.org>
1 file changed