[FR]: Warn user on unrecognized config options

[jonoff]

Is your feature request related to a problem? Please elaborate.

As new features are created, the user's config.yml file is bound to become outdated sooner or late, currently it warns/creates missing options that are required. It'd be nice if it also warned the user when an deprecated/unrecognized option is cluttering up their config file.

Describe the solution you'd like

A warning could be displayed for each deprecated/unrecognized config found. If it's an previously-used option, it could even hint to the user to refer a wiki page, IE: https://github.com/StuffAnThings/qbit_manage/wiki/v4-Migration-Guide

Does your solution involve any of the following?

• New config option
• New command option

Describe alternatives you've considered

Just manually compare the sample config file to my current one

Who will this benefit?

Anyone who isn't aware of changes or doesn't update often.

Additional Information

I found another config documentation issue, there is a comment in the sample which suggests the remote_dir option shouldn't be set, but when I unset it, it gets autoset:

[check_for_attribute:371] [WARNING] | Config Warning: directory sub-attribute remote_dir not found,