Add note on testing to types affected by Japanese calendar era change

[rpetrusha]

Add note on testing to types affected by Japanese calendar era change

The following types are affected by the forthcoming era change in the Japanese and Japanese Lunisolar calendars:

• System.DateTime
• System.DateTimeOffset
• System.Globalization.Calendar
• System.Globalization.DateTimeFormatInfo
• System.Globalization.JapanseseCalendar
• System.Globalizatiopn.JapaneseLunisolarCalendar

In addition, the conceptual [Working with Calendars] topic is affected.

A note should be added to the type topics and the single conceptual topic that recommends testing for the new Japanese calendar era on Windows systems, and that links to "Prepare your application for the Japanese era change", which is to be published in the Windows Dev Center.