Add missing dependency on drracket (for docs)

[SuzanneSoy]

On my machine (racket v6.9.0.4 20170517-8bc9cef7a9), raco setup -iDxn --check-pkg-deps gives:

.raco-wrapped: --- checking package dependencies ---
.raco-wrapped: found undeclared dependency:
.raco-wrapped:   mode: build (of documentation)
.raco-wrapped:   for package: "debug"
.raco-wrapped:   on package: "drracket"
.raco-wrapped:   from document: "debug"
.raco-wrapped:   to document: "drracket"

[AlexKnauth]

This dependency is caused by this seclink:
https://github.com/AlexKnauth/debug/blob/master/debug/scribblings/debug.scrbl#L61-L65

@seclink["Language" #:doc '(lib "scribblings/drracket/drracket.scrbl")]

Will adding an #:indirect? #true argument make the dependency go away?

[SuzanneSoy]

I guess it would work, yes. I suppose you do not want to add the dependency so that debug can be installed on headless systems?

[AlexKnauth]

Hopefully this is now fixed by 6c5f1cb