Update page.mdx (#7048)

CORE-0000

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## PR-Codex overview
This PR updates the `preferredProvider` options in the `detailsModal` configuration for the `connectbutton` component, enhancing payment provider flexibility.

### Detailed summary
- Modified `preferredProvider` options in `detailsModal`:
  - Removed `"KADO"`
  - Added `"COINBASE"`

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Author: saminacodes

apps/portal/src/app/connect/pay/customization/connectbutton/page.mdx

@@ -95,7 +95,7 @@ You can specify which onramp provider to present to your users. By default, we c
 	client={client}
 	detailsModal={{
 		payOptions: {
-			preferredProvider: "STRIPE" | "KADO" | "TRANSAK",
+			preferredProvider: "STRIPE" | "TRANSAK" | "COINBASE",
 		},
 	}}
 />