upd attribute kind keys

CHANGELOG.md

@@ -21,6 +21,11 @@
 | ```<<"type">>``` | ```checkbox``` | ```"checkbox"``` |
 | ```<<"type">>``` | ```toolbar``` | ```"toolbar"``` |
 | ```<<"type">>``` | ```context``` | ```"context"``` |
+| ```<<"kind">>``` | ```subtitles``` | ```"subtitles"``` |
+| ```<<"kind">>``` | ```captions``` | ```"captions"``` |
+| ```<<"kind">>``` | ```descriptions``` | ```"descriptions"``` |
+| ```<<"kind">>``` | ```chapters``` | ```"chapters"``` |
+| ```<<"kind">>``` | ```metadata``` | ```"metadata"``` |
 
 
 ##### 6.6.2-erl19

src/elements/embed/element_track.erl

@@ -73,11 +73,11 @@ render_element(Record) ->
     
     {<<"kind">>,
        case Record#track.kind of
-         "subtitles" -> "subtitles";
-         "captions" -> "captions";
-         "descriptions" -> "descriptions";
-         "chapters" -> "chapters";
-         "metadata" -> "metadata";
+         subtitles -> "subtitles";
+         captions -> "captions";
+         descriptions -> "descriptions";
+         chapters -> "chapters";
+         metadata -> "metadata";
          _ -> []
        end},