Remove out of date copyright & license notice

- Copyright statements are not necessary.. Further, ours is years out of
date (up to 2021). Rather than maintaining that, we can simplify and remove.

- License text is removed, it is pretty duplicative. We have a footer link
for the full license, we need the license spelled out on our home page.

index.html

@@ -19,21 +19,3 @@ <h2>The World's Foremost Open Source Grand Strategy Game</h2>
     <a href="{{ '/maps-list/maps/' | prepend: site.baseurl }}"><img src="./images/triplea_promo.png" alt="Screenshot of TripleA" width="1059" height="798"></a>
  </div>
 
-<h2>License</h2>
-
-<p>
-Copyright (C) 2001-2021 TripleA contributors.
-</p>
-<p>
-This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public
-License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later
-version.
-</p>
-<p>
-This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
-warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
-</p>
-<p>
-The complete license notice is available
-<a href="https://github.com/triplea-game/triplea/blob/master/README.md#license">here</a>.
-</p>