Merge pull request #33184 from bogdanvlviv/document-year_format-option-of-date_select

Add to docs mention about `:year_format` option of date select

actionview/lib/action_view/helpers/date_helper.rb

@@ -205,6 +205,7 @@ def time_ago_in_words(from_time, options = {})
       # * <tt>:end_year</tt>          - Set the end year for the year select. Default is <tt>Date.today.year + 5</tt> if
       #   you are creating new record. While editing existing record, <tt>:end_year</tt> defaults to
       #   the current selected year plus 5.
+      # * <tt>:year_format</tt>       - Set format of years for year select. Lambda should be passed.
       # * <tt>:discard_day</tt>       - Set to true if you don't want to show a day select. This includes the day
       #   as a hidden field instead of showing a select field. Also note that this implicitly sets the day to be the
       #   first of the given month in order to not create invalid dates like 31 February.
@@ -275,6 +276,9 @@ def time_ago_in_words(from_time, options = {})
       #   # Generates a date select with custom prompts.
       #   date_select("article", "written_on", prompt: { day: 'Select day', month: 'Select month', year: 'Select year' })
       #
+      #   # Generates a date select with custom year format.
+      #   date_select("article", "written_on", year_format: ->(year) { "Heisei #{year - 1988}" })
+      #
       # The selects are prepared for multi-parameter assignment to an Active Record object.
       #
       # Note: If the day is not included as an option but the month is, the day will be set to the 1st to ensure that