Issue:
Bug: Docs: Adding redirect URL details



Documentation didn't have any details about the Redirect URL.

Pull request description:
## Type of Change
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- [ ] Bugfix
- [ ] New feature
- [ ] Enhancement
- [ ] Refactoring
- [ ] Dependency updates
- [X] Documentation
- [ ] CI/CD

## Description
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### Additional Changes

- [ ] This PR modifies the API contract
- [ ] This PR modifies the database schema
- [ ] This PR modifies application configuration/environment variables

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2. `crates/router/src/configs`
3. `loadtest/config`
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## Motivation and Context
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Closes #5506 

## How did you test it?
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## Checklist
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- [ ] I formatted the code `cargo +nightly fmt --all`
- [ ] I addressed lints thrown by `cargo clippy`
- [ ] I reviewed the submitted code
- [ ] I added unit tests for my changes where possible


Testing:

Patch:
diff --git a/crates/api_models/src/payments.rs b/crates/api_models/src/payments.rs
index a466288b416..09fede09e5d 100644
--- a/crates/api_models/src/payments.rs
+++ b/crates/api_models/src/payments.rs
@@ -2978,7 +2978,6 @@ where
                 | PaymentMethodDataResponse::MandatePayment {}
                 | PaymentMethodDataResponse::GiftCard {}
                 | PaymentMethodDataResponse::PayLater(_)
-                | PaymentMethodDataResponse::Paypal {}
                 | PaymentMethodDataResponse::RealTimePayment {}
                 | PaymentMethodDataResponse::Upi {}
                 | PaymentMethodDataResponse::Wallet {}
@@ -3005,7 +3004,6 @@ pub enum PaymentMethodDataResponse {
     BankTransfer {},
     Wallet {},
     PayLater(Box<PaylaterResponse>),
-    Paypal {},
     BankRedirect {},
     Crypto {},
     BankDebit {},