Rollup merge of #154515 - sayantn:std-detect-notify, r=tgross35

Notify stdarch maintainers on changes in std_detect

cc @Amanieu @folkertdev @Kobzol

It would be nice to be notified when std_detect changes, as it is spiritually a part of stdarch.

Also assign @rust-lang/libs to std_detect

Author: GuillaumeGomez