Fix inconsistent documentation comment to match code implementation

[peterxjang-stripe]

Summary

Fixed documentation comments

Motivation

Comments were incorrectly stating that a function returns an object with two fields when it only has a single field (in two separate instances). These comments are used in generating the API reference docs, which can cause implementation errors for users.
https://stripe.dev/stripe-react-native/api-reference/functions/confirmPlatformPaySetupIntent.html
https://stripe.dev/stripe-react-native/api-reference/functions/confirmPlatformPayPayment.html

Testing

• I tested this manually
• I added automated tests
• N/A

Documentation

Select one:

• I have added relevant documentation for my changes.
• This PR does not result in any developer-facing changes.
• This is a documentation change.