Issue:
doc: add `React demo` app link

## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [ ] New feature
- [x] Enhancement
- [ ] Refactoring
- [ ] Dependency updates

## Description

Add new quick start option for trying out hyperswitch, with `React Demo App`
<!-- Describe your changes in detail -->


### Additional Changes

- [ ] 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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## How did you test it?
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## Checklist
<!-- Put an `x` in the boxes that apply -->

- [ ] I formatted the code `cargo +nightly fmt --all`
- [ ] I addressed lints thrown by `cargo clippy`
- [ ] I reviewed submitted code
- [ ] I added unit tests for my changes where possible
- [ ] I added a [CHANGELOG](/CHANGELOG.md) entry if applicable


Resolution:
<think>
PR Context:
- Title: docs: fix quick start guide and update dashboard link
- Merged: 2023-01-22T18:46:24Z
- Files changed: 5 files
- Commits: 3 commits

Implementation approach:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [x] Refactoring

## Description
<!-- Describe your changes in detail -->
- Make the option to three ( it was not updated in this PR #452 )
- Replace the dashboard link from https://dashboard-hyperswitch.netlify.app/ to https://app.hyperswitch.io/



## How did you test it?
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</think>

To implement this, you'll need to modify:


**Detailed Implementation:**


**Commit 1:** docs: fix quick start guide and update dashboard link (#454)
Files to modify:


**crates/router/src/openapi.rs**
  Modify existing code