Protected packages: Remove developer as an example from documentation

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What does this MR do and why?

After switching to a positive logic for package protection rules, developer is no longer a valid value for minimum_access_level_for_push.

We need to update the documentation for the REST API to reflect this change.

REST API issue: #457512 (closed)

🛠 with ❤ at Siemens

MR acceptance checklist

MR Checklist ( @nwittstruck)

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• [] Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the javascript style guides
• [] Conforms to the database guides

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