Issue:
docs(openapi): document path parameters for API keys endpoints

## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [ ] New feature
- [x] Enhancement
- [ ] Refactoring
- [ ] Dependency updates

## Description
<!-- Describe your changes in detail -->
This PR documents the path parameters added to the API keys endpoints in #600.

## Motivation and Context
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Why is this change required? What problem does it solve?
If it fixes an open issue, please link to the issue here.

If you don't have an issue, we'd recommend starting with one first so the PR
can focus on the implementation (unless its an obvious bug or documentation fix
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Documenting the path parameters correctly makes it easier for users to try out our APIs via the SwaggerUI preview.

## How did you test it?
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Did you write an integration/unit/API test to verify the code changes?
Or did you test this change manually (provide relevant screenshots)?
-->
Generated the OpenAPI specification locally, tested the rendered Swagger UI preview.

## Checklist
<!-- Put an `x` in the boxes that apply -->

- [x] I formatted the code `cargo +nightly fmt --all`
- [x] I addressed lints thrown by `cargo clippy`
- [x] 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: release: Update CHANGELOG for release v0.5.0
- Merged: 2023-03-21T09:28:58Z
- Files changed: 1 files
- Commits: 1 commits

Implementation approach:
# 0.5.0 (2023-03-21)

## Build System / Dependencies

* **deps:**  update deps (#734) (16bc886c)

## Chores

* **merchant_account:**  remove `api_key` field (#713) (230fcdd4)
* **config:**  move connector base URLs under the `[connectors]` table (#723) (df8c8b5a)
*  address Rust 1.68 clippy lints (#728) (1ffabb40)

## Continuous Integration

* **release:**  specify `fetch-depth` for code checkout and use official Docker GitHub actions (#722) (c451368f)

## Documentation Changes

</think>

To implement this, you'll need to modify:


(No detailed commit information available)