Role of "optional packages" not clear from initial documentation

[dabrahams]

Description

I haven't read the whole doc yet, but just at the top, I see:

    ;; optional packages if you want to use :hydra, :el-get, :blackout,,,
    (leaf hydra :ensure t)
    (leaf el-get :ensure t)
    (leaf blackout :ensure t)

Now, leaf being a system for using other packages, it's not clear to me what's special about these particular packages that I'd want to list them at this point in leaf initialization. I hope I'm making some sense. The comment could do something to clarify this point.

[conao3]

All it means is that you can use special keywords for those packages in leaf-keyword, but you need the corresponding package to use the special keywords. Better explanations are welcome!

[dabrahams]

🤷 Near as I can tell from a quick scan of leaf-keywords.el, using these special keywords have implications beyond what would be implied by simply using leaf to load the package in the "normal way" (the same as any arbitrary package not covered by leaf-keywords). But I don't know what those implications are, so can't possibly offer a better explanation.