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/en/usage/ytdlp.md

@@ -0,0 +1,40 @@
+---
+title: "yt-dlp Video Download"
+weight: 7
+---
+
+# yt-dlp Video Download
+
+{{< hint warning >}}
+This feature requires the yt-dlp command-line tool installed on your system.
+{{< /hint >}}
+
+Use the `/ytdlp` command to download videos and audio from supported video websites, including YouTube, Bilibili, Twitter, and 1000+ other sites.
+
+```bash
+/ytdlp <url1> [url2] [flags...]
+```
+
+Examples:
+
+```bash
+# Basic download
+/ytdlp https://www.youtube.com/watch?v=dQw4w9WgXcQ
+
+# Download multiple videos
+/ytdlp https://www.youtube.com/watch?v=video1 https://www.youtube.com/watch?v=video2
+
+# Use custom parameters
+/ytdlp https://www.youtube.com/watch?v=dQw4w9WgXcQ -f best
+/ytdlp https://www.youtube.com/watch?v=dQw4w9WgXcQ --extract-audio --audio-format mp3
+```
+
+Common parameters:
+
+- `-f <format>`: Specify download format (e.g., `best`, `worst`, `bestvideo+bestaudio`)
+- `--extract-audio`: Extract audio
+- `--audio-format <format>`: Audio format (e.g., `mp3`, `m4a`, `wav`)
+- `--write-sub`: Download subtitles
+- `--write-thumbnail`: Download thumbnail
+
+For more parameters, see [yt-dlp documentation](https://github.com/yt-dlp/yt-dlp#usage-and-options).