User:GTrang/To do/2021


 * ✅ Add 2020 to the "Historical years" cateory and update its description.
 * ✅ Remove 2021 from the "Future years" category and update its description.
 * ✅ Update the bold link in the "Years in century" template to refer to 2021 instead of 2020.
 * ✅ Update holiday pages to refer to 2021 instead of 2020.
 * ✅ Show state admission dates on the corresponding year pages, with those year pages then being added to the "U.S. state admission years" category.
 * ✅ Create at least one page about a calendar concept.
 * ✅ Create templates that automatically determine the calendar for any year in the Julian or Gregorian calendar.
 * ✅ (by HolidaysBot for the AD year pages and manually for the BC year pages) Apply those templates to year pages except for the year 1582.
 * ✅ Include calendars on holiday pages.
 * ✅ Show the years when some holidays became federal holidays.
 * ✅ Show links to the preceding and following century categories on century category pages.
 * ✅ Link the corresponding year pages in the lead sections of some holiday pages.