[help-texinfo] texinfo : HTML (dir) link is bad

[spam . spam . spam . spam]

Hello,

I try the short sample which is gived in the manual for GNU Texinfo (version
4.13, 18 September 2008).

I generate the HTML :
$makeinfo --html sample.texinfo

Then I watch it in my web browser :
$firefox sample/index.html &

The problem is that there is a link "(dir)" to go to "../index.html#dir", and
this file isn't generated by makeinfo, so it doesn't exists.

How to correct this link please?

Thank you.