Backport LaTex version of r60651:

Fix documentation for Calendar.iterweekdays(): firstweekday is a property.
Fixes second part of #2018.

Doc/lib/libcalendar.tex

@@ -38,8 +38,8 @@ subclasses.
 
 \begin{methoddesc}{iterweekdays}{weekday}
 Return an iterator for the week day numbers that will be used
-for one week. The first number from the iterator will be the
-same as the number returned by \method{firstweekday()}.
+for one week. The first value from the iterator will be the same
+as the value of the \member{firstweekday} property.
 \end{methoddesc}
 
 \begin{methoddesc}{itermonthdates}{year, month}