Besides adding docstrings to `patroni.config`, a few side changes
have been applied:
* Reference `config_file` property instead of internal attribute
`_config_file` in method `_load_config_file`;
* Have `_AUTH_ALLOWED_PARAMETERS[:2]` as default value of `params`
argument in method `_get_auth` instead of using
`params or _AUTH_ALLOWED_PARAMETERS[:2]` in the body;
* Use `len(PATRONI_ENV_PREFIX)` instead of a hard-coded `8` when
removing the prefix from environment variable names;
* Fix documentation of `wal_log_hints` setting. The previous docs
mentioned it was a dynamic setting that could be changed. However
it is managed by Patroni, which forces `on` value.
References: PAT-123.
* Further nested lists rendering fixes
* Remove a couple of sphinx warnings
* Fix bootstrap.users.password description
* Boto->boto3 in README's
* Split configuration docs and move some lines across files
* Fix a typo
