bug#46979: Allow setting Man-default-entry via Local Variables

[積丹尼 Dan Jacobson]

>>>>> "EZ" == Eli Zaretskii <eliz@gnu.org> writes:
>> From: 積丹尼 Dan Jacobson
>> <jidanni@jidanni.org>
>> Date: Sun, 07 Mar 2021 07:18:12 +0800
>> 
>> Well wouldn't it be great if one could do e.g.,
>> 
>> # Local Variables:
>> # Man-default-entry: "crontab(5)"
>> # End:
>> 
>> in one's .crontab file...

EZ> IMO, it would make much more sense to derive that from the current
EZ> major-mode (in Man-default-man-entry).  Patches welcome.

OK, sounds good. But sometimes e.g., crontab mode is not in emacs
officially yet, so supplementing that should still be an option.