Remove README.md from docs preview workflow triggers

[kubabuczak]

Description

What does this PR have in it?

Key Changes

Highlight the updates in specific files

Testing and Verification

How did you test these changes? What automated tests are added?

Related Issues

Jira tickets, GitHub issues, Support tickets...

PR Checklist

• Code changes adhere to the project's coding standards.
• Relevant unit and integration tests are included.
• Documentation has been updated accordingly.
• All tests pass locally.
• The PR description follows the project's guidelines.

[github-actions]

📝 Documentation preview deployed!

🔗 Preview URL: https://splunk.github.io/splunk-operator/

[coveralls]

Pull Request Test Coverage Report for Build 19501191831

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 86.544%

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Totals
Change from base Build 19501182401:	0.0%
Covered Lines:	10709
Relevant Lines:	12374

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💛 - Coveralls