Update cs file to use devsite-compatible lowercase lang ids.

Change-Id: Ie20e5977464199648fd91515ebe71c250162c0ee
diff --git a/tools/droiddoc/templates-sdk/docpage.cs b/tools/droiddoc/templates-sdk/docpage.cs
index b6d808d..90e663b 100644
--- a/tools/droiddoc/templates-sdk/docpage.cs
+++ b/tools/droiddoc/templates-sdk/docpage.cs
@@ -28,24 +28,24 @@
     <?cs if:training ?>
       <div class="training-nav-top layout-content-col span-5" itemscope itemtype="http://schema.org/SiteNavigationElement">
         <a href="#" class="prev-page-link hide"
-            zh-TW-lang="上一堂課"
-            zh-CN-lang="上一课"
+            zh-tw-lang="上一堂課"
+            zh-cn-lang="上一课"
             ru-lang="Предыдущий"
             ko-lang="이전"
             ja-lang="前へ"
             es-lang="Anterior"               
             >Previous</a>
         <a href="#" class="next-page-link hide"
-            zh-TW-lang="下一堂課"
-            zh-CN-lang="下一课"
+            zh-tw-lang="下一堂課"
+            zh-cn-lang="下一课"
             ru-lang="Следующий"
             ko-lang="다음"
             ja-lang="次へ"
             es-lang="Siguiente"               
             >Next</a>
         <a href="#" class="start-class-link hide"
-            zh-TW-lang="開始上課"
-            zh-CN-lang="开始"
+            zh-tw-lang="開始上課"
+            zh-cn-lang="开始"
             ru-lang="Начало работы"
             ko-lang="시작하기"
             ja-lang="開始する"
@@ -55,16 +55,16 @@
     <?cs elif:!page.trainingcourse ?>
       <div class="paging-links layout-content-col span-4" itemscope itemtype="http://schema.org/SiteNavigationElement">
         <a href="#" class="prev-page-link hide"
-            zh-TW-lang="上一堂課"
-            zh-CN-lang="上一课"
+            zh-tw-lang="上一堂課"
+            zh-cn-lang="上一课"
             ru-lang="Предыдущий"
             ko-lang="이전"
             ja-lang="前へ"
             es-lang="Anterior"               
             >Previous</a>
         <a href="#" class="next-page-link hide"
-            zh-TW-lang="下一堂課"
-            zh-CN-lang="下一课"
+            zh-tw-lang="下一堂課"
+            zh-cn-lang="下一课"
             ru-lang="Следующий"
             ko-lang="다음"
             ja-lang="次へ"
@@ -132,16 +132,16 @@
         <div class="paging-links layout-content-col col-4">
           <?cs if:(design||training||guide||walkthru) && !page.landing && !page.trainingcourse && !footer.hide ?>
             <a href="#" class="prev-page-link hide"
-                zh-TW-lang="上一堂課"
-                zh-CN-lang="上一课"
+                zh-tw-lang="上一堂課"
+                zh-cn-lang="上一课"
                 ru-lang="Предыдущий"
                 ko-lang="이전"
                 ja-lang="前へ"
                 es-lang="Anterior"               
                 >Previous</a>
             <a href="#" class="next-page-link hide"
-                zh-TW-lang="下一堂課"
-                zh-CN-lang="下一课"
+                zh-tw-lang="下一堂課"
+                zh-cn-lang="下一课"
                 ru-lang="Следующий"
                 ko-lang="다음"
                 ja-lang="次へ"