Updated YTDL_OPTIONS Cookbook (markdown)

YTDL_OPTIONS-Cookbook.md

@@ -9,6 +9,17 @@ Embeds English subtitles and chapter markers (for videos that have them), change
       - 'YTDL_OPTIONS={"writesubtitles":true,"subtitleslangs":["en","-live_chat"],"updatetime":false,"postprocessors":[{"key":"Exec","exec_cmd":"chmod 0664","when":"after_move"},{"key":"FFmpegEmbedSubtitle","already_have_subtitle":false},{"key":"FFmpegMetadata","add_chapters":true}]}'
 ```
 
+### Embed metadata
+
+Contributed by [@PikuZheng](https://github.com/PikuZheng).
+
+NOTE: May cause errors for non-Youtube videos.
+
+```yaml
+    environment:
+      - 'YTDL_OPTIONS={ "ignoreerrors":true, "writethumbnail":true, "postprocessors":[  {"key":"FFmpegMetadata","add_metadata":true,"add_chapters":true,"add_infojson":"if_exists"}, {"key":"EmbedThumbnail"}]}'
+```
+
 ### Automatically marking MeTube downloads with SponsorBlock chapters
 
 Contributed by [@loomweaver](https://github.com/loomweaver).