rename `example` to `gamemode-simulate-game`

Signed-off-by: Stephan Lachnit <stephanlachnit@protonmail.com>

example/meson.build

@@ -1,6 +1,6 @@
 # An example game
 executable(
-    'example',
+    'gamemode-simulate-game',
     sources: [
         'main.c',
     ],