Document valid values of the char type#93493

Merged

bors merged 3 commits intorust-lang:masterfrom GKFX:char-docs-2

Feb 2, 2022

+108-10

Commits on Jan 30, 2022

Document char validity
GKFX
committed

Commits on Jan 31, 2022

(rust-lang#93493 ) Add items from code review
GKFX
committed

Commits on Feb 1, 2022

Fix annotation of code blocks
GKFX
committed