Rewrite Opt-in Page explainer for review request campaigns

I suggest you rewrite the explainer text for the Opt-in Page option for review request campaigns. Here is my suggested rewrite:

"Opt-in Page

If you need your customers to opt-in before they receive review invitations from you, they can use the form on the opt-in page.

Once the form is submitted, they'll be added to your review request campaign."

It's a bit longer, but also a bit clearer, minimizing confusion over this option.