Adds Chinese Simplified to the language drop-down (#1357)

Graduates the Chinese Simplified translation to the language drop-down
selector. Part of #324

src/running-the-course/translations.md

@@ -4,6 +4,7 @@ The course has been translated into other languages by a set of wonderful
 volunteers:
 
 * [Brazilian Portuguese][pt-BR] by [@rastringer], [@hugojacob], [@joaovicmendes], and [@henrif75].
+* [Chinese (Simplified)][zh-CN] by [@suetfei], [@wnghl], [@anlunx], [@kongy], [@noahdragon], [@superwhd], and [@SketchK].
 * [Korean][ko] by [@keispace], [@jiyongp], and [@jooyunghan].
 * [Spanish][es] by [@deavid].
 
@@ -16,7 +17,6 @@ recently updated translations:
 
 * [Bengali][bn] by [@raselmandol].
 * [Chinese (Traditional)][zh-TW] by [@hueich], [@victorhsieh], [@mingyc], and [@johnathan79717].
-* [Chinese (Simplified)][zh-CN] by [@suetfei], [@wnghl], [@anlunx], [@kongy], [@noahdragon], [@superwhd], and [@SketchK].
 * [French][fr] by [@KookaS] and [@vcaen].
 * [German][de] by [@Throvn] and [@ronaldfw].
 * [Japanese][ja] by [@CoinEZ-JPN] and [@momotaro1105].

theme/index.hbs

@@ -180,6 +180,9 @@
                           <li role="none"><button role="menuitem" class="theme">
                               <a id="pt-BR">Brazilian Portuguese (Português do Brasil)</a>
                           </button></li>
+                          <li role="none"><button role="menuitem" class="theme">
+                              <a id="zh-CN">Chinese Simplified (汉语)</a>
+                          </button></li>
                           <li role="none"><button role="menuitem" class="theme">
                               <a id="ko">Korean (한국어)</a>
                           </button></li>