Add XML documentation for Android.Ranging.Ble.CS

The `Android.Ranging.Ble.CS` namespace contains **95** `To be added` placeholders in source XML documentation (excluding `docs\xml\index.xml`).

Example command:

```powershell
rg -n -i --glob 'Android.Ranging.Ble.CS/**' --glob 'ns-Android.Ranging.Ble.CS.xml' 'to be added' docs\xml
```

## Update log

- 2026-09-10: Refreshed the placeholder scan from **91** to **95** (increased by **4**). Related documentation PRs: [#644](https://github.com/dotnet/android-api-docs/pull/644).

Start with the provided rg command under docs\xml to enumerate the 95 placeholders in the Android.Ranging.Ble.CS namespace, excluding docs\xml\index.xml. Review the matching XML documentation entries and their surrounding API names before documenting them. Done means the namespace no longer contains those "To be added" placeholders and the scan returns no matches.

Written by the indexing model from the issue text.