contents/index: add a link to the showcase

Author: hajimehoshi

contents/index.html

@@ -53,7 +53,7 @@ <h3>High Performance</h3>
   </div>
   <div class="grid-item-2">
     <h3>Production-Ready</h3>
-    <p class="img"><img src="/images/productionready.png" width="448" height="224" alt="Production Ready"></p>
+    <p class="img"><a href="/en/showcase.html"><img src="/images/productionready.png" width="448" height="224" alt="Production Ready"></a></p>
     <p>Ebitengine has been used to develop production-level games. One such example is <a href="https://daigostudio.com/bearsrestaurant/">Bear's Restaurant</a>, a mobile application that has been downloaded over 1,500,000 times. See the showcase page for more production games made with Ebitengine. For information on other commercial games by Ebitengine, please visit <a href="/en/showcase.html">the showcase page</a>.</p>
   </div>
 </div>

contents/ja/index.html

@@ -53,7 +53,7 @@ <h3>高いパフォーマンス</h3>
   </div>
   <div class="grid-item-2">
     <h3>商用レベルのゲーム</h3>
-    <p class="img"><img src="/images/productionready.png" width="448" height="224" alt="Production Ready"></p>
+    <p class="img"><a href="/ja/showcase.html"><img src="/images/productionready.png" width="448" height="224" alt="Production Ready"></a></p>
     <p>Ebitengine は商用レベルのゲームを作ることができます。<a href="https://daigostudio.com/bearsrestaurant/">くまのレストラン</a>は、 150 万ダウンロードを達成した Ebitengine 製のモバイルゲームです。その他の Ebitengine 製商用ゲームについては<a href="/ja/showcase.html">ショーケース</a>のページをご覧ください。</p>
   </div>
 </div>