add donation link

home.html

@@ -60,6 +60,7 @@
             <a class="dropdown-menu-item groupmessages selectable_theme theme_original theme_calm" href="#">Group Messages</a>
             <a class="dropdown-menu-item" href="https://github.com/twisterarmy/twister-html/issues" target="_blank">Feedback</a>
             <a class="dropdown-menu-item" href="https://twisterarmy.github.io" target="_blank">Project Website</a>
+            <a class="dropdown-menu-item" href="https://twisterarmy.github.io/donate" target="_blank">Donate</a>
           </div>
         </a>
       </li>

network.html

@@ -47,6 +47,7 @@
               <a class="dropdown-menu-item updates-check-client">Check for client's updates</a>
               <a class="dropdown-menu-item" href="https://github.com/twisterarmy/twister-html/issues" target="_blank">Feedback</a>
               <a class="dropdown-menu-item" href="https://twisterarmy.github.io" target="_blank">Project Website</a>
+              <a class="dropdown-menu-item" href="https://twisterarmy.github.io/donate" target="_blank">Donate</a>
            </div>
           </a>
         </li>