document side-effects of importing std++

5 jobs for master
Status Job ID Name Coverage
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canceled #4503
fp-timing
build-coq.8.6

canceled #4502
fp-timing
build-coq.8.6.1

canceled #4501
fp-timing
build-coq.8.7

canceled #4500
fp-timing
build-coq.8.7.dev

 
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canceled #4504
opam