Update TourKit README to correct primaryButton example and formatting

[mattsherman]

All Submissions:

• Have you followed the WooCommerce Contributing guideline?
• Does your code follow the WordPress' coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

This PR makes two small changes to the TourKit README...

• Correct primaryButton config in example code
• Improve formatting of example code (fix indentation)

How to test the changes in this Pull Request:

• Have you followed the Writing high-quality testing instructions guide?

1. Verify example for primaryButton is correct (see Show spotlight when switching to variable product type #37413 for an example of code)
2. Verify example formatting is improved (indentation).

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes, as applicable?
• Have you created a changelog file for each project being changed, ie pnpm --filter=<project> changelog add?
• Have you included testing instructions?

FOR PR REVIEWER ONLY:

• I have reviewed that everything is sanitized/escaped appropriately for any SQL or XSS injection possibilities. I made sure Linting is not ignored or disabled.

[github-actions]

Hi @chihsuan, @woocommerce/mothra

Apart from reviewing the code changes, please make sure to review the testing instructions as well.

You can follow this guide to find out what good testing instructions should look like:
https://github.com/woocommerce/woocommerce/wiki/Writing-high-quality-testing-instructions

[github-actions]

Test Results Summary

Commit SHA: 5ec5d74

Test 🧪	Passed ✅	Failed 🚨	Broken 🚧	Skipped ⏭️	Unknown ❔	Total 📊	Duration ⏱️
API Tests	259	0	0	2	0	261	0m 49s
E2E Tests	191	0	0	10	0	201	16m 36s

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To view the full API test report, click here.
To view the full E2E test report, click here.
To view all test reports, visit the WooCommerce Test Reports Dashboard.

[chihsuan]

Thanks, LGTM! 💯