Add XML documentation for Android.Telephony.Data

The `Android.Telephony.Data` namespace contains **330** `To be added` placeholders in source XML documentation (excluding `docs\xml\index.xml`).

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

## Update log

- 2026-09-10: Refreshed the placeholder scan from **360** to **330** (reduced by **30**). Related documentation PRs: [#449](https://github.com/dotnet/android-api-docs/pull/449), [#452](https://github.com/dotnet/android-api-docs/pull/452), [#615](https://github.com/dotnet/android-api-docs/pull/615), [#644](https://github.com/dotnet/android-api-docs/pull/644).