Issue #sb-000: default value updated for transcript_file_format (#3364)

ansible/roles/stack-sunbird/templates/sunbird_player.env

@@ -149,7 +149,7 @@ dock_default_video_size={{ dock_default_video_size | default(15000) }}
 sunbird_kong_refresh_token_api=https://{{sunbird_domain_name}}/auth/v1/refresh/token
 use_sunbird_kong_token={{dock_use_sunbird_kong_token | default('true')}}
 sunbird_transcript_supported_languages={{sunbird_transcript_supported_languages | default('[{"language":"English","languageCode":"en"},{"language":"Hindi","languageCode":"hi"},{"language":"Assamese","languageCode":"as"},{"language":"Bengali","languageCode":"bn"},{"language":"Gujarati","languageCode":"gu"},{"language":"Kannada","languageCode":"ka"},{"language":"Marathi","languageCode":"mr"},{"language":"Odia","languageCode":"or"},{"language":"Tamil","languageCode":"ta"},{"language":"Telugu","languageCode":"te"}]')}}
-sunbird_transcript_file_format={{sunbird_transcript_file_format | default('srt')}}
+sunbird_transcript_file_format={{sunbird_transcript_file_format | default('vtt')}}
 sunbird_transcript_required={{sunbird_transcript_required | default('false')}}
 
 #release-4.5.0