Add note about sponsorship cancellation when switching enterprise plan

When an organization upgrades or switches their enterprise plan, the
existing payment method is not carried forward. This note warns users
that active paid subscriptions, including GitHub Sponsors sponsorships,
are automatically cancelled if a new payment method is not added before
the next billing cycle.

Closes github/docs-content#22561

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: slincoln75

content/organizations/managing-organization-settings/upgrading-to-the-github-customer-agreement.md

@@ -24,6 +24,9 @@ You can upgrade to the {% data variables.product.company_short %} Customer Agree
 1. In the text field, type the name of the company, non-profit, or group that owns the organization account. This is the entity that will enter into an agreement with {% data variables.product.prodname_dotcom %}.
 1. To agree to the {% data variables.product.company_short %} Customer Agreement on behalf of your entity, click **Accept terms**.
 
+> [!NOTE]
+> When you upgrade or switch your enterprise plan, your existing payment method is not carried forward. If you do not add a new payment method before your next billing cycle, active paid subscriptions—including {% data variables.product.prodname_sponsors %} sponsorships—are automatically cancelled. To avoid disruption, add a payment method immediately after upgrading. For more information, see "[AUTOTITLE](/billing/how-tos/set-up-payment/manage-payment-info)" and "[AUTOTITLE](/billing/concepts/third-party-payments/github-sponsors)."
+
 ## Further reading
 
 * [AUTOTITLE](/free-pro-team@latest/site-policy/github-terms/github-terms-of-service)