Lint and format Swift code

[cclauss]

Why:

Demonstrate how to lint and format Swift code.

Closes: ISSUE_NUMBER

What's being changed (if available, include any code snippets, screenshots, or gifs):

Added commands to int and format Swift code.

Check off the following:

• A subject matter expert (SME) has reviewed the technical accuracy of the content in this PR. In most cases, the author can be the SME. Open source contributions may require an SME review from GitHub staff.
• The changes in this PR meet the docs fundamentals that are required for all content.
• All CI checks are passing and the changes look good in the preview environment.

[github-actions]

👓 Previews for changed content

This comment is 🤖 automatically generated and will be overwritten every time changes are committed to this branch.

The table contains an overview of files in the content directory that have been changed in this pull request. It's provided to make it easy to review your changes on the review server. Please note that changes to the data directory will not show up in this table.

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Content directory changes

You may find it useful to copy this table into the pull request summary. There you can edit it to share links to important articles or changes and to give a high-level overview of how the changes in your pull request support the overall goals of the pull request.

Source	Preview	Production	What Changed
actions/use-cases-and-examples/building-and-testing/building-and-testing-swift.md	fpt ghec ghes@ 3.15 3.14 3.13 3.12 3.11 3.10	fpt ghec ghes@ 3.15 3.14 3.13 3.12 3.11 3.10

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Key: fpt: Free, Pro, Team; ghec: GitHub Enterprise Cloud; ghes: GitHub Enterprise Server
This table is posted from the Content Changes Table Comment workflow.

[subatoi]

Thank you for opening a PR! Per our “About contributing to GitHub Docs” article -

We only document GitHub products, features, tools, and extensions. We may mention or link to third-party tools to demonstrate how a feature works, but we do not accept pull requests to document third-party tools or integrations unless they were codeveloped with GitHub.

For this reason, we will be closing this PR. If you would like to update our docs with content outside of third-party tools or integrations, feel free to open another PR or issue 💛