docs: add v6 Rokt migration guidance

[denischilik]

Background

Adds v6 migration guidance for Rokt API ownership and type updates so integrators can move to the new kit-owned API surface without changing call flow.

What Has Changed

• Documented that Rokt APIs are now owned by rokt-kit while access remains MParticle.getInstance().Rokt()
• Added mapping from removed mParticle Rokt wrapper types to native com.rokt.roktsdk types
• Clarified that imports should use com.mparticle.kits.Rokt for app-facing code
• Documented that Rokt.prepareAttributesAsync(...) is internal and no longer public API

Screenshots/Video

N/A

Checklist

• I have performed a self-review of my own code.
• I have made corresponding changes to the documentation.
• I have added tests that prove my fix is effective or that my feature works.
• I have tested this locally.

Additional Notes

Documentation-only change.

[cursor]

PR Summary

Low Risk
Low risk documentation-only update; no runtime code changes. Risk is limited to potential integrator confusion if the new import/type mappings are incorrect.

Overview
Adds v6 migration guidance for Rokt integrations: clarifies that the Rokt API surface is now owned by rokt-kit while access remains MParticle.getInstance().Rokt(), and updates example imports to com.mparticle.kits.Rokt.

Documents removal of mParticle Rokt wrapper types (e.g., MpRoktEventCallback, RoktConfig, PlacementOptions) and maps integrators to the corresponding native com.rokt.roktsdk types, and notes that Rokt.prepareAttributesAsync(...) is now internal and not part of the public API.

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud