Re: doc elisp intro cross reference fixes

[Richard Stallman]

    Is the main point of the node still accurate?

        When you specified a variable using the @code{defvar} special
        form, you could distinguish a readily settable variable from
        others by typing an asterisk, @samp{*}, in the first column of its
        documentation string.  ....

The use of the * is not obsolete, but it is vital also to document
proper use of defcustom.