Black/whitelist examples in rules documentation use "characters" when they mean "classes"

[stuartpb]

See https://github.com/opws/opws-schemata/blob/82799027df007c5d0002aecb11762de891eeac3d/v0.2/docs/rules.md

I haven't looked at the schema in a while, but I'm pretty sure this is a (repeated) typo, and probably one that applies to the v0.1 documentation, too (since v0.2 was basically just v0.1, but with a few fields added to cover details that were previously kept in out-of-schema fields).