[DE] added translation

Signed-off-by: Maxim Kadushkin <maxim.kadushkin@onlyoffice.com>

apps/documenteditor/main/app/controller/Viewport.js

@@ -251,7 +251,7 @@ define([
                     mnuitemHideRulers.hide();
 
                 me.header.menuItemsDarkMode = new Common.UI.MenuItem({
-                    caption: 'Dark mode',
+                    caption: me.txtDarkMode,
                     checkable: true,
                     checked: Common.UI.Themes.isContentThemeDark(),
                     value: 'mode:dark'
@@ -453,6 +453,7 @@ define([
         },
 
         textFitPage: 'Fit to Page',
-        textFitWidth: 'Fit to Width'
+        textFitWidth: 'Fit to Width',
+        txtDarkMode: 'Dark mode'
     }, DE.Controllers.Viewport));
 });

apps/documenteditor/main/locale/en.json

@@ -1227,6 +1227,7 @@
   "DE.Controllers.Toolbar.txtSymbol_zeta": "Zeta",
   "DE.Controllers.Viewport.textFitPage": "Fit to Page",
   "DE.Controllers.Viewport.textFitWidth": "Fit to Width",
+  "DE.Controllers.Viewport.txtDarkMode": "Dark mode",
   "DE.Views.AddNewCaptionLabelDialog.textLabel": "Label:",
   "DE.Views.AddNewCaptionLabelDialog.textLabelError": "Label must not be empty.",
   "DE.Views.BookmarksDialog.textAdd": "Add",