[Request] `--help` output should include (optional) listing of config properties

It would be really nice if the Agent's various configuration properties (keys, default values, optionality, and descriptions) were embedded into the sources in some way that could be iterated over dynamically at runtime and dumped as help output. This would remove the need to manually maintain a separate README document listing.

Start by locating the Agent's --help handling and the source definitions for its configuration properties, then compare them with the separately maintained README listing. Define how keys, default values, optionality, and descriptions are represented and iterated at runtime. Done means help can optionally print this complete configuration information without requiring a separate manually maintained list.

Written by the indexing model from the issue text.