Simplify to have single reference for configs in docs + templatize where possible

[ejm714]

We should have one canonical place for configurations in the docs. Currently, configuration params are documented multiple times and this means it can be easy for the docs to conflict or get out of date.

For example, configurations are specified twice in configurations.md (help text + paragraph form) in addition to the API reference zamba.models.config.

Relatedly, we should consider templatizing the cli help in quickstart.md as well as in the DensePose models page so this always uses the latest and does not require manual updates.