[racket] red underline of language name

> In #lang scribble/manual, if I type
>
> @codeblock{
> #lang racket
> }
>
> the output (in HTML) has the word "racket" underlined, which seems
> fair enough;

I see this is the case if I run scribble manually:

   scribble --html some-file.scrbl

However, the red underline shows up, not because it doesn't know that
a binding exists, but because it knows a binding exists but doesn't
know how to connect the reference to its documentation.


You can provide additional referencing information to scribble with
the  ++xref-in option to scribble.

For example:

    scribble --html ++xref-in setup/xref load-collections-xref some-file.scrbl

after which the red underline should be replaced with the proper
hyperlink to the Racket language reference.