User-facing documentation on configuring logging

[clokep]

The the document we currently link to (docs.python.org/3.7/library/logging.config.html#configuration-dictionary-schema) isn't particularly user-friendly, especially to people unfamiliar with python. It also talks about "configuration dictionaries" in the abstract, rather than dealing specifically with yaml configuration files, so some of the examples are misleading. It would be good to provide better user-facing documentation of how to configure logging.

Split out of #7125