Update traits.dd

[RazvanN7]

After [1] is merged and @future is documented, this addition should be the next step.

[1] dlang/dmd#7232

[dlang-bot]

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[andralex]

cc @WalterBright

[RazvanN7]

@andralex all the other true/false occurrences are highlighted with $D. Anyway, it's not important...

[andralex]

Yah, most of the docs predate the introduction of the backticks feature. This gave me the idea of dlang/phobos#5801.

[leandro-lucarella-sociomantic]

I think it's worth noting that this is an experimental feature. To the point that it's not even @future yet, but @__future (IIRC). Also, I think we should strongly state that this is not intended for user code yet, and link to the DIP.

I think this feature is having too much visibility and too little clarity for an experimental feature...