Refactor configuration to use snake_case for all options, and extract documentation settings to own file

[caendesilva]

Changes to the configuration files

The entire configuration system has been refactored.

Snake_case is used for all configuration keys

All configuration keys are now in the snake_case_format. Published configuration files will need to be updated accordingly. This is pretty fast in a modern code editor like VS Code.

Documentation options have been moved to a new file

The documentation page specific options have been moved to the config/docs.php file.
You may need to republish Blade views if you have done so before.

This is also easy to do in a modern code editor. See this example of the search and replace I used
to update the codebase:

hyde.docs_sidebar_header_title => docs.header_title

Deprecations and removals

The deprecated option named hyde.docs_directory has been removed.

Use docs.output_directory instead.

The authors.yml has been deprecated, and will be refactored in an upcoming release.