docs: Add GDateTime to the GLib API reference

docs/reference/glib/glib-docs.sgml

@@ -76,6 +76,7 @@ synchronize their operation.
       <xi:include href="xml/checksum.xml" />
       <xi:include href="xml/i18n.xml" />
       <xi:include href="xml/date.xml" />
+      <xi:include href="xml/date-time.xml" />
       <xi:include href="xml/random_numbers.xml" />
       <xi:include href="xml/hooks.xml" />
       <xi:include href="xml/misc_utils.xml" />

docs/reference/glib/glib-sections.txt

@@ -1407,6 +1407,68 @@ g_date_monday_weeks_in_year
 g_date_sunday_weeks_in_year
 </SECTION>
 
+<SECTION>
+<FILE>gdatetime</FILE>
+G_TIME_SPAN_DAY
+G_TIME_SPAN_HOUR
+G_TIME_SPAN_MINUTE
+G_TIME_SPAN_SECOND
+G_TIME_SPAN_MILLISECONT
+GTimeSpan
+<SUBSECTION>
+GDateTime
+g_date_time_new_full
+g_date_time_new_from_date
+g_date_time_new_from_epoch
+g_date_time_new_from_timeval
+g_date_time_new_now
+g_date_time_new_utc_now
+g_date_time_new_today
+g_date_time_copy
+g_date_time_ref
+g_date_time_unref
+<SUBSECTION>
+g_date_time_add
+g_date_time_add_days
+g_date_time_add_full
+g_date_time_add_hours
+g_date_time_add_milliseconds
+g_date_time_add_minutes
+g_date_time_add_months
+g_date_time_add_seconds
+g_date_time_add_weeks
+g_date_time_add_years
+<SUBSECTION>
+g_date_time_difference
+g_date_time_compare
+g_date_time_equal
+g_date_time_hash
+<SUBSECTION>
+g_date_time_get_day_of_month
+g_date_time_get_day_of_week
+g_date_time_get_day_of_year
+g_date_time_get_dmy
+g_date_time_get_hour
+g_date_time_get_julian
+g_date_time_get_microsecond
+g_date_time_get_millisecond
+g_date_time_get_minute
+g_date_time_get_month
+g_date_time_get_second
+g_date_time_get_utc_offset
+g_date_time_get_timezone_name
+g_date_time_get_year
+g_date_time_is_daylight_savings
+g_date_time_is_leap_year
+<SUBSECTION>
+g_date_time_day
+g_date_time_to_local
+g_date_time_to_epoch
+g_date_time_to_timeval
+g_date_time_to_utc
+g_date_time_printf
+</SECTION>
+
 <SECTION>
 <TITLE>Hook Functions</TITLE>
 <FILE>hooks</FILE>