Fix booktable in std.traits

[wilzbach]

I just noticed that quite many traits aren't publicly documented, but listed in the booktable and on the other site, there are publicly documented ones, which aren't listed.

What's the story here? Were they maybe just accidentally set to public?
And what's the point behind SharedInoutOf? What would be wrong with SharedOf!(InoutOf!int)?

[PetarKirov]

Let's see if closing & reopening the PR will force Jenkins to re-run the pipeline.

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