Align docs with current IAP SDK versions

[Armaxis]

Summary

• Update README to reflect current SDK versions: iOS 1.6.5, Android 1.6.8
• Update docs/get-started.md Android version override example from 1.6.6 to 1.6.8
• Add changelog entry for the version alignment

No code or dependency changes — docs only.

Test plan

• Verify README shows correct versions
• Verify get-started guide shows correct Android version in the override example

🤖 Generated with Claude Code

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