Add XML documentation for Android.Hardware.Display

The `Android.Hardware.Display` namespace contains **287** `To be added` placeholders in source XML documentation (excluding `docs\xml\index.xml`).

Example command:

```powershell
rg -n -i --glob 'Android.Hardware.Display/**' --glob 'ns-Android.Hardware.Display.xml' 'to be added' docs\xml
```

## Update log

- 2026-09-10: Refreshed the placeholder scan from **232** to **287** (increased by **55**). Related documentation PRs: [#644](https://github.com/dotnet/android-api-docs/pull/644).

Run the provided rg command against docs\xml to enumerate the 287 placeholders under Android.Hardware.Display, excluding docs\xml\index.xml. Review the matching namespace and API XML entries to determine the missing reference text. Done means the targeted To be added placeholders have been replaced with Android.Hardware.Display documentation and the placeholder scan no longer reports them.

Scritto dal modello di indicizzazione a partire dal testo della issue.