docs: Add documentation for various features including Aria2, direct download links, parsers, storage rules, silent mode, storage transfer, chat watching, and yt-dlp video download

- Created new markdown files for Aria2 download, direct download links, parsers, storage rules, silent mode, storage transfer, chat watching, and yt-dlp video download.
- Included usage examples, configuration instructions, and detailed explanations for each feature.
- Translated documentation into Chinese for accessibility.

docs/content/zh/usage/ytdlp.md

@@ -0,0 +1,40 @@
+---
+title: "yt-dlp 视频下载"
+weight: 7
+---
+
+# yt-dlp 视频下载
+
+{{< hint warning >}}
+该功能需要在系统中安装 yt-dlp 命令行工具.
+{{< /hint >}}
+
+使用 `/ytdlp` 命令可以下载支持的视频网站的视频和音频, 支持 YouTube、Bilibili、Twitter 等 1000+ 个网站.
+
+```bash
+/ytdlp <url1> [url2] [flags...]
+```
+
+示例:
+
+```bash
+# 基本下载
+/ytdlp https://www.youtube.com/watch?v=dQw4w9WgXcQ
+
+# 下载多个视频
+/ytdlp https://www.youtube.com/watch?v=video1 https://www.youtube.com/watch?v=video2
+
+# 使用自定义参数
+/ytdlp https://www.youtube.com/watch?v=dQw4w9WgXcQ -f best
+/ytdlp https://www.youtube.com/watch?v=dQw4w9WgXcQ --extract-audio --audio-format mp3
+```
+
+常用参数:
+
+- `-f <format>`: 指定下载格式 (如 `best`, `worst`, `bestvideo+bestaudio`)
+- `--extract-audio`: 提取音频
+- `--audio-format <format>`: 音频格式 (如 `mp3`, `m4a`, `wav`)
+- `--write-sub`: 下载字幕
+- `--write-thumbnail`: 下载缩略图
+
+更多参数请参考 [yt-dlp 文档](https://github.com/yt-dlp/yt-dlp#usage-and-options).