Document that older Android versions have unmitigatable security risks on our supported platforms page

[Hixie]

Subcomponent of flutter/flutter#63559.

We should update our public documentation to mention that versions of Android older than Android 9 (aka Pie, SDK level 28) leave applications vulnerable to the StrandHogg attack, and then link to https://developer.android.com/privacy-and-security/risks/strandhogg.

[Hixie]

cc @mariamhas

[flutter-triage-bot]

This issue is assigned to @reidbaker and @mariamhas but has had no recent status updates. Please consider unassigning this issue if it is not going to be addressed in the near future. This allows people to have a clearer picture of what work is actually planned. Thanks!

[flutter-triage-bot]

This issue is assigned to @reidbaker but has had no recent status updates. Please consider unassigning this issue if it is not going to be addressed in the near future. This allows people to have a clearer picture of what work is actually planned. Thanks!

[reidbaker]

This will be a flutter/website change.

[antfitch]

Transferred this to the website. Maybe we add a note here:
https://docs.flutter.dev/get-started/install/linux/android

@sfshaza2 what do you think? This seems like an Android issue, not a Flutter issue. But it also seems like a pretty serious issue.

[ash2moon]

@antfitch I added this PR #11829 to add a new page for vulnerabilities.