[Mailer] [Resend] Add Resend webhook signature verification

[fabpot]

Q	A
Feature PR	symfony/symfony#54525
PR author(s)	@welcoMattic
Merged in	7.1

We created this issue to not forget to document this new feature. We would really appreciate if you can help us with this task. If you are not sure how to do it, please ask us and we will help you.

To fix this issue, please create a PR against the 7.1 branch in the symfony-docs repository.

Thank you! 😃

[xabbuh]

Is there anything to document here? This rather looks like an internal change to me.

[welcoMattic]

It looks like just adding a line in this table

My bad, I looked at 7.0 doc version. In 7.x it's already there, so no need to update anything. We can close.

To be explicit: Resend webhooks were handled in the first PR, but without signature verification.