Update index.md

Author: ice-nuclearcrackhead239

collections/pixel-art-tools/index.md

@@ -16,6 +16,7 @@ items:
  - Kully/pixel-paint
  - pixa-pics/pixa-pics.github.io
  - Mateusz-Nejman/Pixed
+ - counter185/voidsprite
 display_name: Pixel Art Tools
 created_by: leereilly
 image: pixel-art-tools.png