Add minimal WebVTT syntax file

syntax/vtt.vim

@@ -0,0 +1,25 @@
+" Vim syntax file
+" Language:	Web Video Text Tracks Format (VTT)
+" Filenames:	*.vtt
+" Vim syntax file
+" SeeAlso:      <https://developer.mozilla.org/en-US/docs/Web/API/WebVTT_API>
+" Maintainer:   Alexander Gehrke
+" Created:      2023-12-19
+
+if version < 600
+  syntax clear
+elseif exists("b:current_syntax")
+  finish
+endif
+
+syn region vttComment start="^NOTE .*" end="^$"
+syn match vttTimings "\d\{2}:\d\{2}\.\d\{3}"
+syn match vttArrow "-->"
+syn keyword vttHeader WEBVTT
+
+hi def link vttTimings   Number
+hi def link vttArrow     Special
+hi def link vttComment   Comment
+hi def link vttHeader    Keyword
+
+let b:current_syntax = "vtt"