Hi,

The attached patch fix the type declaration of org-capture-templates by
allowing the user to use file, variable, function and sexp as target's
file to match the documentation

(org) Template elements
> Most target specifications contain a file name. If that file name is the
> empty string, it defaults to ‘org-default-notes-file’. A file can also
> be given as a variable, function, or Emacs Lisp form.

OK to push?