Add option for opting to add specific text at the end of cross post

[ahangarha]

I am planning to almost leave twitter. Yet, I want to use my account there to not only cross post my toots but also inform people that I am posting on mastodon so if they want to get in touch with me, they can come to mastodon.

I think this can be done by adding some customizable text as an extra tweet after the cross posted tweet in which the link to the toot can also be added. It would be up to the user to opt in or not.