Changes in datetimepicker to accepts formats in options

config/locales/picker.en.yml

@@ -3,10 +3,10 @@ en:
   datetime_picker:
     date:
       label: Date
-      placeholder: "YYYY-MM-DD"
+      placeholder: "YYYY/MM/DD"
     default:
       label: Date and time
-      placeholder: "YYYY-MM-DD HH:MM"
+      placeholder: "YYYY/MM/DD HH:MM"
     separated:
       label: Date and time
     time:

config/locales/picker.zh_tw.yml

@@ -3,10 +3,10 @@ zh_tw:
   datetime_picker:
     date:
       label: 日期
-      placeholder: "YYYY-MM-DD"
+      placeholder: "YYYY/MM/DD"
     default:
       label: 日期和時間
-      placeholder: "YYYY-MM-DD HH:MM"
+      placeholder: "YYYY/MM/DD HH:MM"
     separated:
       label: 日期和時間
     time: