Docs: remove unneeded author attributions (#145002)

These directives are not maintained and misleadingly indicate individual
rather than community ownership.

See https://github.com/python/docs-community/issues/180 for discussion,
and https://github.com/python/devguide/pull/1740 for an update to the
devguide.

Also ensured that everyone is in the Misc/ACKS file.