fix: Fixed context menu text inconsistency, b=bug #10016, c=tabs

Author: mr-cheffy

locales/en-US/browser/browser/zen-vertical-tabs.ftl

@@ -18,7 +18,7 @@ zen-toolbar-context-compact-mode-hide-both =
     .label = Hide both
     .accesskey = H
 zen-toolbar-context-new-folder =
-    .label = New folder
+    .label = New Folder
     .accesskey = N
 
 sidebar-zen-expand =