docs(flutter,android): keep the push subscription open in README samples

[ChiragAgg5k]

What does this PR do?

The Flutter and Android README Push samples call subscription.unsubscribe() right after subscribing, so copying them tears the subscription down before any message can arrive. The samples now keep the subscription, and a sentence says to unsubscribe when you stop listening (dispose() / onDestroy()).

Raised by Hansi on the README-only SDK PR appwrite/sdk-for-flutter#342.

Test Plan

• php example.php flutter client and php example.php android client, then read the Push section of each generated README
• Confirmed unsubscribe() exists on the generated Flutter and Android push subscriptions
• composer lint-twig, composer refactor:check, ./.github/scripts/max-line-length.sh . 1200 "*.twig"

Related PRs and Issues

• docs: refresh README sdk-for-flutter#342
• docs: refresh README sdk-for-android#144

Closes #2101

[hansi-codes]

🟢 Tier S · Ready to merge

The documentation changes correctly preserve the subscription and give an appropriate cleanup point.

The Flutter and Android Push README samples now keep the returned subscription instead of immediately unsubscribing. Each README also explains when to unsubscribe as part of ending message handling.

Verdict	New comments	Fixed	Still open
✅ Approved	0	0	0

📂 Walkthrough · 2

File	Change
templates/android/README.md.twig	Keeps the Push subscription active and documents unsubscribing when the activity stops listening.
templates/flutter/README.md.twig	Keeps the Push subscription active and documents unsubscribing when the widget stops listening.

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_{Reviewed b4ea883 · Details · Comment @hansi-codes review to re-run, or mention @hansi-codes with a question.}

[hansi-codes]

🟢 Tier S · Looks good to merge. Summary