Add XML documentation for Javax.Net.Ssl

The `Javax.Net.Ssl` namespace contains **160** `To be added` placeholders in source XML documentation (excluding `docs\xml\index.xml`).

```powershell
rg -n -i --glob 'Javax.Net.Ssl/**' --glob 'ns-Javax.Net.Ssl.xml' 'to be added' docs\xml
```

## Update log

- 2026-09-10: Refreshed the placeholder scan from **180** to **160** (reduced by **20**). Related documentation PRs: [#377](https://github.com/dotnet/android-api-docs/pull/377), [#409](https://github.com/dotnet/android-api-docs/pull/409), [#574](https://github.com/dotnet/android-api-docs/pull/574), [#644](https://github.com/dotnet/android-api-docs/pull/644).

首先对 docs\xml 运行提供的 rg 命令，然后检查 Javax.Net.Ssl/** 下以及 ns-Javax.Net.Ssl.xml 中包含这 160 个占位符的文件。将占位符替换为准确的 XML 文档，并重新运行扫描，以确认目标条目均已覆盖。

由索引模型根据 Issue 内容生成。