[README.md] Document format_id field in output template section (#6557)

[youtube-dl] / README.md

diff --git a/README.md b/README.md
index 02b9775f9743f2db53a70d2bd0f55d1453d93c2e..8fa402ee28a93b2485c4a81d4c4d73fb5f891272 100644 (file)
--- a/README.md
+++ b/README.md
@@ -108,7 +108,7 @@ which means you can modify it, redistribute it or use it however you like.
     --playlist-reverse               Download playlist videos in reverse order
     --xattr-set-filesize             Set file xattribute ytdl.filesize with expected filesize (experimental)
     --hls-prefer-native              Use the native HLS downloader instead of ffmpeg (experimental)
-    --external-downloader COMMAND    Use the specified external downloader. Currently supports aria2c,curl,httpie,wget
+    --external-downloader COMMAND    Use the specified external downloader. Currently supports aria2c,axel,curl,httpie,wget
     --external-downloader-args ARGS  Give these arguments to the external downloader
 
 ## Filesystem Options:
@@ -272,6 +272,7 @@ The `-o` option allows users to indicate a template for the output file names. T
  - `autonumber`: The sequence will be replaced by a five-digit number that will be increased with each download, starting at zero.
  - `playlist`: The name or the id of the playlist that contains the video.
  - `playlist_index`: The index of the video in the playlist, a five-digit number.
+ - `format_id`: The sequence will be replaced by the format code specified by `--format`.
 
 The current default template is `%(title)s-%(id)s.%(ext)s`.