Update screenshot of forking workflow

What does this MR do?

!35592 (merged) introduced new improved UI for forking project. Last-minute changes there made screenshot a bit outdated (primary green buttons were swapped with "secondary"). This MR makes docs in-sync with current codebase

Related issues

#212456 (closed)

Author's checklist (required)

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Review checklist

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1. Primary Reviewer

• Review by a code reviewer or other selected colleague to confirm accuracy, clarity, and completeness. This can be skipped for minor fixes without substantive content changes.

2. Technical Writer

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