docs: Note rejected SDK key retry in the initialization matrix row

[kinyoklion]

Summary

LaunchDarkly Python SDK 9.18.0 made a rejected SDK key retryable rather than permanently stopping the data source. The README says start_wait=0 waits "until the data source becomes valid or permanently fails", but a rejected key now never permanently fails. With zero, initialize therefore never completes while the key is rejected.

• Initialization row: now ⚠️, notes the SDK 9.18.0 behavior, and marks the provider gap (zero should mean "do not wait", per OFP 4.3.6), tracked by #64.
• The start_wait paragraph gets the same note.

Details

I checked this locally with launchdarkly-server-sdk 9.18.1 and an invalid key. The data source stayed INITIALIZING, and last_error reported ERROR_RESPONSE 401 while it retried. It never reported OFF.

The provider allows launchdarkly-server-sdk >=9.17.0,<10, so new installs get the retry behavior. #64 also edits these lines. Whichever merges second will need a small README conflict fix.

Found in the weekly OpenFeature provider audit. Docs-only change.

Link to Devin session: https://app.devin.ai/sessions/c8bc4e80339b473882c2dddffe981edf
Open in Devin Desktop: https://app.devin.ai/desktop/session/c8bc4e80339b473882c2dddffe981edf?variant=devin
Requested by: @kinyoklion

[devin-ai-integration]

I'll fix CI failures and address comments from users with write access. I'll skip comments containing "(aside)".

• Disable automatic comment, CI, and merge conflict monitoring