bug#31063: 27.0.50; improve help for advised functions

[Juri Linkov]

>>>>> (eval-defun EDEBUG-IT)
>>>>>
>>>>> :override advice: ‘edebug-eval-defun’
>>>>
>>>> (where ":override advice:" is highlighted in orange)
>>>>
>>>> Could we please remove (or amend) the orange color for readability,
>>>
>>> I also removed the warning face, but feel free to put that back if
>>> somebody thinks that this deserves a warning.  It seemed a bit too
>>> dramatic to me.
>>
>> It could have a link on ":override advice:" clicking on which will
>> visit the advice definition.
>
> That would be nice.  Do we have that information?

I remember that old defadvice had some link in the Help buffer, but
now I can't confirm this.  But for new nadvice maybe this will work:
if a piece of advice is at least a function defined by `defun' then
maybe it's possible to display the body of advice with a link to the
function defined by `defun'?