Update update-billing-info.mdx

src/content/docs/fundamentals/subscriptions-and-billing/update-billing-info.mdx

@@ -121,3 +121,17 @@ To update your billing email address:
 3. Go to **Invoices & Documents**.
 4. For **Billing email preference**, select **Change email address**.
 5. Enter and confirm your new email and select **Save**.
+
+## Pay an invoice manually
+
+There may be times when you will want to manaully pay an invoice
+
+To pay an invoice manually:
+
+1. Log in to your Cloudflare account
+2. Click on the Profile icon at the top right
+3. Click on “Billing”
+4. If you see an unpaid invoice click on it
+5. From within the invoice, click the “Pay Online” link
+6. You will then be redirected to the BIlling system where you can proceed with your payment
+7. Once the payment is made you should be able to make any desired changes to your subscription including downgrades and cancelation that are in adherence with Cloudflare policies