document -- and @code @findex and `` and ---

[Dumas Patrice]

Hi,

I had a look at the texinfo-4.6 manual after I read the thread about 
-- in defvar, and I think that the following should go in the manual:

-- is changed to - in normal text info files
---, -- `` and '' are kept as is 
  in @code, @kbd, ...
  in index entries formatted as code (@findex, @vindex...) 
  in definition arguments
  in menu comments

And so one if I forgot some place.

Pat