This is a resource pack made to replace the normal, pretty dull, doors with new fancier glass doors.
It's also helpful for multiplayer and being able to see if, and who, is behind any given door.
Most importantly it looks good, with updated new-default textures. (Jappa Textures)
Current Version: v5 made for Minecraft 1.16 (from 1.7 - 1.14+)
Check out the Planet Minecraft Post
Or the Minecraft Forum Post
(I don't keep the forums post updated much these days)