Clarify pledge checkout button wording

This article covers gifts made through GiveCampus. Payment and recurring-gift options depend on the institution and the form.

The pre-payment form settings expose Form Button Text, used by the standard checkout button; Complete Pledge is a default assigned when a pledge form is created. Replace it with a concise label such as Continue to Payment within the 20-character limit, and add explanatory form text that donor details come before payment details. Review both pay-now and pay-later pledge paths so the label is accurate for the enabled options. Some accelerated/default-payment buttons have their own label behavior; preview the actual donor flow.