fix: FDv2 initializer readiness

[joker23]

Requirements

• I have added test coverage for new or changed functionality
• I have followed the repository's pull request submission guidelines
• I have validated my changes against all supported platform versions

Describe the solution you've provided

This PR will:

1. Make it so that a client in FDv2 will only report intialized when it gets a basis + valid selector. This will align the behavior better with the FDv2 initializer specs.
2. Updated the docs for the custom datasystem options with an example for clarity

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