[README.md] Add format_id to the list of string meta fields available for use in...

diff --git a/README.md b/README.md
index 52b2a85a3b97b4d822a46d091cd96b8b733f1760..e972bf69f8aedc6ec235f7f50a83e8ac5b951994 100644 (file)
--- a/README.md
+++ b/README.md
@@ -600,6 +600,7 @@ Also filtering work for comparisons `=` (equals), `!=` (not equals), `^=` (begin
  - `vcodec`: Name of the video codec in use
  - `container`: Name of the container format
  - `protocol`: The protocol that will be used for the actual download, lower-case. `http`, `https`, `rtsp`, `rtmp`, `rtmpe`, `m3u8`, or `m3u8_native`
+ - `format_id`: A short description of the format
 
 Note that none of the aforementioned meta fields are guaranteed to be present since this solely depends on the metadata obtained by particular extractor, i.e. the metadata offered by video hoster.