Rollup merge of rust-lang#102177 - inquisitivecrystal:std-doc-typo, r=Dylan-DPC

Fix a typo in `std`'s root docs

Remarkably, this typo has been present for *seven years.* I was so surprised that I reread the text five times and then asked people on the rust Zulip to double-check. :)

Author: matthiaskrgr