VTT Subtitle files support for video-KirbyTag

It would be very neat if the (video:…)-KirbyTag added support for subtitles in VTT format.

Suggestion:
(video filename.mp4 subtitles: true) searches for a filename.mp4.vtt file in the same directory and adds it to the video tag. Additionally, it shold also search for

^filename\.[A-z]{5}\.vtt (filename dot five letter language code dot vtt) to find filename.de-DE.vtt, filename.en-UK.vtt, filename.en-US, etc. and add all of them too.