bug#13572: 24.3.50; `describe-function' -> "This function has a compiler macro..."

[Drew Adams]

> this is a type predicate constructed
> automatically for a register defstruct.
> 
> The doc needs to be improved for this kind of thing 
> (automatically generated functions).

I guess Common Lisp defstruct does not allow for a doc string for the generated
predicate (unlike the case for slots, constructor functions, and the defstruct
itself).

It would be good if Emacs Lisp could automatically generate a minimal doc string
for the predicate that at least referred to the structure.  Something like this:

 "Type predicate for a NAME structure."

where NAME is the defstruct name.

I guess that would be a wishlist item, since this is not part of the CL spec.

Apart from that, in this particular defstruct it would be good to at least add
doc strings for those things that allow it.  A doc string for the defstruct
itself is the least users could ask for.