Subscription status list in CLI docs is missing values

[sgillies]

https://planet-sdk-for-python-v2.readthedocs.io/en/latest/cli/cli-subscriptions/#subscription-results

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The available statuses are created, queued, processing, failed, and success. Note it's quite useful to use jq to help filter out results as well.
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But ...

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planet subscriptions list --status asdf
Usage: planet subscriptions list [OPTIONS]
Try 'planet subscriptions list --help' for help.

Error: Invalid value for '--status': 'asdf' is not one of 'running', 'cancelled', 'preparing', 'pending', 'completed', 'suspended', 'failed'.
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The error message lists the correct statuses, but the docs do not.

https://developers.planet.com/docs/subscriptions/#subscription-status

[tbarsballe]

The SDK docs should probably just link to the subscription docs as a source-of-truth.

[asonnenschein]

#1062