doc(ios): add device.model quirks

[erisu]

Platforms affected

ios

Motivation and Context

closes #147

Description

Updated documentation to explain the iOS quirks.

Testing

n/a

Checklist

• I've run the tests to see all new and existing tests pass
• I added automated test coverage as appropriate for this change
• Commit is prefixed with (platform) if this change only applies to one platform (e.g. (android))
• If this Pull Request resolves an issue, I linked to the issue in the text above (and used the correct keyword to close issues using keywords)
• I've updated the documentation if necessary