docs: update man page

man/waybar-clock.5.scd

@@ -138,6 +138,11 @@ View all valid format options in *strftime(3)* or have a look https://en.cpprefe
 :[ When enabled, the calendar follows the ISO 8601 standard: weeks begin on
    Monday, and the first week of the year is numbered 1. The default week format is
    '{:%V}'.
+|[ *first-day-of-week*
+:[ integer
+:[
+:[ The first day of the week, where 0 is Sunday and 6 is Saturday.
+   When not set, the first day of the week is determined by the locale settings.
 
 3. Addressed by *clock: calendar: format*
 [- *Option*
@@ -210,6 +215,7 @@ View all valid format options in *strftime(3)* or have a look https://en.cpprefe
 		"mode"             : "year",
 		"mode-mon-col"     : 3,
 		"weeks-pos"        : "right",
+		"first-day-of-week": 1,
 		"on-scroll"        : 1,
 		"on-click-right"   : "mode",
 		"format": {