use singular "subtitle" when referring to track type

1 files changed, 1 insertions, 1 deletions

diff --git a/doc/api.md b/doc/api.md
index 67809cb..2d0dd9a 100644
--- a/doc/api.md
+++ b/doc/api.md
@@ -142,7 +142,7 @@ export interface SegmentInfo {
   duration: number;
   tracks: TrackInfo[];
 }
-export type TrackKind = "video" | "audio" | "subtitles";
+export type TrackKind = "video" | "audio" | "subtitle";
 export interface TrackInfo {
   name?: string;
   language?: string;