[Datetime-SIG] Clearing up terminology

[Tim Peters]

Correcting an error, albeit an inconsequential one:

[Tim]
> - Since you start in Chicago standard time, I expect that (assuming
> it's implemented) some spelling.of is_dst will record "no, it's not
> DST" in your dt object.  That will never change across the duration of
> the program.  There is no spelling of is_dst today.

s/Chicago standard time/Chicago daylight time/
s/no, it's not/yes, it is/