bug#37538: [PATCH] Add docstring for `tags-complete-tags-table-file'.

[Hong Xu <hong@topbug.net>]

On 10/10/19 12:49 AM, Eli Zaretskii wrote:
>> Cc: larsi@gnus.org, 37538@debbugs.gnu.org
>> From: Hong Xu <hong@topbug.net>
>> Date: Wed, 9 Oct 2019 15:58:46 -0700
>>
>>> I actually don't understand why we would like to send the reader to
>>> the manual, instead of describing the effects of WHAT in the doc
>>> string.  Can we just say it right there?
>>>
>>
>> The description was quite long and I don't think it is justifiable to copy so much text over here to the docstring, plus there are additional reference in the referred manual section.
> 
> If you show me what long description you had in mind, I could try
> saying that more concisely as appropriate for a doc string.
> 

This snippet in Programmed Completion section:

    • A flag specifying the type of completion operation to perform; see
      *note Basic Completion::, for the details of those operations.
      This flag may be one of the following values.

      ‘nil’
           This specifies a ‘try-completion’ operation.  The function
           should return ‘nil’ if there are no matches; it should return
           ‘t’ if the specified string is a unique and exact match; and
           it should return the longest common prefix substring of all
           matches otherwise.

      ‘t’
           This specifies an ‘all-completions’ operation.  The function
           should return a list of all possible completions of the
           specified string.

      [other kinds of values]