Update copywrite (#75)

Author: SimonDarksideJ

templates/monogame/partials/footer.tmpl.partial

@@ -61,7 +61,7 @@
 
         <div class="d-flex flex-column flex-sm-row justify-content-between align-items-center gap-3 py-4 my-4">
             <div>
-                Copyright © 2009-2024 MonoGame Foundation, Inc. <br/> Designed with
+                © 2009-2024 MonoGame Foundation, Inc. is a 501(c)(3) non-profit. EIN 93-3803929<br/>Designed with
                 <span class="text-danger">❤</span>
                 by
                 <a href="https://github.com/MonoGame/monogame.github.io/graphs/contributors">MonoGame Community</a>