krel/announce: ask for confirmation before sending the email
krel/announce: ask for confirmation before sending the email

The changes preserve the existing behavior when --nomock is not passed.
Only when, --nomock is passed, a confirmation is seeked.

Signed-off-by: Nabarun Pal <46a782cbd1e9f752958998187886c2b51fda054c@gmail.com>

kubernetes/release,kubernetes/release