Add option to include FADGI WebVTT header info for caption data

[kmurmur]

Add the option to include the FADGI-defined lightweight metadata tags to give context and define provenance of caption data. The fields and values help patrons and collection administrators understand what kind of data a WebVTT contains, from where it came, and when, where, and how it was made.

Guidelines for Embedding Metadata in WebVTT Files, (PDF 153 KB). Version 1.0. June 7, 2024.