note to reviewers: reply to the original email

A note to reviewers participating in the commit fests: When you send a
review of a patch, reply to the email that contains the patch. Do no
start a new email thread like "Review of 'Some Patch'". This is
important for several reasons:

- It maintains the integrity of the email archives. The commit fest app
is supposed to track discussions, not be a participating link in the
discussions.

- It makes sure the right people get your review. If you start a new
thread, worst case, no one participating in the original thread will see
your email. This is especially true if the original thread and the
commit fest entry have different titles, and you don't even CC the patch
author on your review.

If you don't have the original email in your email client, at least
doctor up the subject line so it looks like a reply, so that email
clients can do a reasonable job sorting the two threads together. Yes,
email is stupid.