Change menu order to mirror game difficulty

As per the front page recommended order:
```
Bandit
Leviathan or Natas or Krypton
Narnia
Behemoth
Utumno
Maze
…
```

_includes/games.md

@@ -1,17 +1,17 @@
 <div id="sidemenu">
     <ul>
         <li><sh>Online</sh></li>
-{% include menu_item.html link="/wargames/vortex" name="Vortex" %}
-{% include menu_item.html link="/wargames/semtex" name="Semtex" %}
-{% include menu_item.html link="/wargames/krypton" name="Krypton" %}
 {% include menu_item.html link="/wargames/bandit" name="Bandit" %}
+{% include menu_item.html link="/wargames/natas" name="Natas" %}
 {% include menu_item.html link="/wargames/leviathan" name="Leviathan" %}
 {% include menu_item.html link="/wargames/narnia" name="Narnia" %}
+{% include menu_item.html link="/wargames/krypton" name="Krypton" %}
 {% include menu_item.html link="/wargames/behemoth" name="Behemoth" %}
 {% include menu_item.html link="/wargames/utumno" name="Utumno" %}
 {% include menu_item.html link="/wargames/maze" name="Maze" %}
+{% include menu_item.html link="/wargames/vortex" name="Vortex" %}
+{% include menu_item.html link="/wargames/semtex" name="Semtex" %}
 {% include menu_item.html link="/wargames/manpage" name="Manpage" %}
-{% include menu_item.html link="/wargames/natas" name="Natas" %}
 {% include menu_item.html link="/wargames/drifter" name="Drifter" %}
 	</ul>
 	<br />