Document that set -v inside case statements is special

[積丹尼 Dan Jacobson]

Please document on the man page somewhere that set -v, +v inside case
statements is special:
$ cat A
case x in x)
              set -v
              : B
              case y in y)
                           set -v
                           : Z
                           ;;
              esac
              ;;
esac
: C
$ bash A
: C

I.e., -v and +v in case statements are remembered, but only have effects
after leaving all case statements. Unlike +x, -x. Same it turns out for dash(1).
Bash 5.1.4.