[Portal] Docs: Update Pay Docs (#5425)

Updated Pay docs to clarify KYC in FAQs

## Problem solved

Short description of the bug fixed or feature added

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## PR-Codex overview
This PR updates the content in the `page.mdx` file to clarify the KYC requirements for using the 'Buy with Fiat' feature in the `Pay` application.

### Detailed summary
- Revised explanation of KYC requirements for `Buy with Fiat`.
- Changed text to specify that KYC is required only for the first purchase, with no further requirements for subsequent purchases on the same platform.

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Author: GiselleNessi

apps/portal/src/app/connect/pay/faqs/page.mdx

@@ -83,7 +83,7 @@ All other tokens will require an additional Buy With Crypto step.
 
 ### How does KYC work with Buy With Fiat
 
-Pay currently requires KYC for first-time purchases. Subsequent purchases will not require KYC.
+Users will be required to complete KYC verification for their first purchase using 'Buy with Fiat.' After that, no further KYC will be needed for future purchases on the same platform.
 
 ### What cryptocurrencies does Pay support?