Update _upload_subtitles.html
Update _upload_subtitles.html

Updated message displayed on template, adding that we do support .vtt subtitles to be uploaded.
ofer43211/unisubs,norayr/unisubs,pculture/unisubs,ReachingOut/unisubs,ofer43211/unisubs,pculture/unisubs,eloquence/unisubs,ReachingOut/unisubs,norayr/unisubs,ofer43211/unisubs,eloquence/unisubs,wevoice/wesub,eloquence/unisubs,ReachingOut/unisubs,norayr/unisubs,eloquence/unisubs,wevoice/wesub,norayr/unisubs,wevoice/wesub,ReachingOut/unisubs,wevoice/wesub,pculture/unisubs,pculture/unisubs,ofer43211/unisubs