add advertisement on site link

resources/lang/en.json

@@ -17,6 +17,7 @@
     "single_player": "Single Player",
     "instructions": "Instructions",
     "how_to_play": "How to Play",
+    "advertise": "Advertise",
     "wiki": "Wiki"
   },
   "help_modal": {

src/client/index.html

@@ -373,6 +373,16 @@
           <a href="/terms-of-service.html" class="t-link" target="_blank">
             Terms of Service
           </a>
+          <p style="text-align: center">
+            <a
+              href="https://www.playwire.com/contact-direct-sales"
+              data-i18n="main.advertise"
+              class="t-link"
+              target="_blank"
+              rel="noopener"
+              >Advertise</a
+            >
+          </p>
         </div>
       </div>
     </footer>