Fix beta builds

The extension's beta name strings were missing.

Change-Id: I0245671c627aced507a9c6460bd6b852aaf1ebaa
diff --git a/src/_locales/zh_CN/messages.json b/src/_locales/zh_CN/messages.json
index fbb6619..438f2a0 100644
--- a/src/_locales/zh_CN/messages.json
+++ b/src/_locales/zh_CN/messages.json
@@ -1,5 +1,6 @@
 {

   "name": {"message": "网页截图"},

+  "name_beta": {"message": "网页截图 (beta)"},

   "description": {"message": "截取网页为图片,支持窗口截图,区域截图和整个网页截图三种方式。支持水平和垂直翻页截取超大网页,新版引进自动截图保存功能。"},

   "default_title": {"message": "网页截图"},

   "capture_screen": {"message": "屏幕区域截图"},