Update slug format in game.json

Author: avivace

entries/rickroll-pcm/game.json

@@ -13,7 +13,7 @@
     "screenshots": [
         "PCM.demo.wgraphics_003.png"
     ],
-    "slug": "rickrollpcm",
+    "slug": "rickroll-pcm",
     "title": "Rickroll PCM",
     "typetag": "demo"
 }