Update the description and picture for STK (#80)

Co-authored-by: Alayan <25536748+Alayan-stk-2@users.noreply.github.com>

Author: Alayan-stk-2

apps/supertuxkart-dev.md

@@ -1,13 +1,17 @@
 # SUPERTUXKART-DEV
 
- SuperTuxKart is a free kart racing game. It focuses on fun and not on realistic kart physics. Instructions can be found on the in-game help page.
+ Karts. Nitro. Action!
+
+ SuperTuxKart is a multi-platform 3D Open Source arcade kart racer with a wide variety of tracks, characters and game modes.
+
+ Play the Story Mode and defeat the evil Nolok, challenge players from all around the world playing online, have fun with up to 8 friends playing together on one PC, explore tracks in egg hunts, challenge yourself in time-trials, race in our official tracks or in hundreds of addons... The choice is yours!
 
  This is the AppImage built on top of the official archive.
 
  This script installs the Pre-release / Developer build.
 
- ![Screenshot](https://upload.wikimedia.org/wikipedia/commons/4/4d/SuperTuxKart_0.8_screenshot.jpg)
- 
+ ![Screenshot](https://supertuxkart.net/assets/wiki/STK1.3_1.jpg)
+
  SITE & SOURCE: https://supertuxkart.net
 
  APPIMAGE: https://github.com/ivan-hc/SuperTuxKart-appimage

apps/supertuxkart.md

@@ -1,10 +1,14 @@
 # SUPERTUXKART
 
- SuperTuxKart is a free kart racing game. It focuses on fun and not on realistic kart physics. Instructions can be found on the in-game help page.
+ Karts. Nitro. Action!
+
+ SuperTuxKart is a multi-platform 3D Open Source arcade kart racer with a wide variety of tracks, characters and game modes.
+
+ Play the Story Mode and defeat the evil Nolok, challenge players from all around the world playing online, have fun with up to 8 friends playing together on one PC, explore tracks in egg hunts, challenge yourself in time-trials, race in our official tracks or in hundreds of addons... The choice is yours!
 
  This is the AppImage built on top of the official archive.
 
- ![Screenshot](https://upload.wikimedia.org/wikipedia/commons/4/4d/SuperTuxKart_0.8_screenshot.jpg)
+ ![Screenshot](https://supertuxkart.net/assets/wiki/STK1.3_1.jpg)
 
  SITE & SOURCE: https://supertuxkart.net