Change "all" icons to "most" icons

Not all icons from game-icons.net are available while the update process isn't automated. I was very confused why they weren't all available after reading this doc!

index.html

         </li>
         <li>
             <code>icon</code>
-            Name of the card icon. You can use all icons from <a href="http://game-icons.net/">game-icons.net</a>.
+            Name of the card icon. You can use most icons from <a href="http://game-icons.net/">game-icons.net</a>.
             For example, the file name of <a href="http://game-icons.net/lorc/originals/plain-dagger.html">this dagger</a>
             is "plain-dagger.png", so you would use "plain-dagger" as the icon name.
             Additional custom icon names are defined in <code>css/custom-icons.css</code>.