Added topic Undertale

I created this because I saw how other topics have fancy things and I wanted the Undertale community here on Github to have this cool thing too. I used a format I saw in most topics used here

Author: Drwhomust

topics/undertale/index.md

@@ -0,0 +1,14 @@
+---
+display_name: Undertale
+topic: undertale
+aliases: UT, under-tale
+related: video-game, role-playing-game, rpg, deltarune, gamemaker, bullet-hell
+short_description: Undertale is a video game created by Toby Fox
+wikipedia_url: https://en.wikipedia.org/wiki/Undertale
+---
+Undertale is a video game by Toby Fox. Released in 2015, The game is about
+the player controlling a small child who fell into a pit near mount ebott.
+And separated by a magical barrier created by the humans in the past.
+You have to go though a journey back to the surface while coming across
+monsters. You can ACT to spare monsters or kill them. There are many endings
+depending on how you play the game