bug#17862: 24.3; regexp-opt docstring is incorrect

[npostavs]

immerrr again <immerrr@gmail.com> writes:

> Sorry about that, other things took priority.

No problem, I thought maybe you had gone on vacation and forgotten all
about this :) It's not really high priority anyway, just that it would
be nice to get it in before the 25.1 release since it's a doc fix.

> +@code{nil}
> +    if all @var{strings} are single-character, the resulting regexp is
> +    not surrounded, otherwise it is surrounded by @samp{\(?:} and
> +    @samp{\)}.

You forgot to update this sentence to be like the one in the docstring.

> +(defun simplified-regexp-opt (strings &optional paren)
> + (let ((parens (cond ((stringp paren)       (cons paren "\\)"))

Oh right, I missed the stringp case in my definition, good catch.

> +nil
> +    the resulting regexp is surrounded by \\(?: and \\), if it is
> +    necessary to ensure that postfix operator appended to it will
                              ^^^
> +    apply to the whole expression.

Missing the word "a" there, I think.  Other than that, looks good to me.