It is not entirely clear to me how I can easily modify or copy a new configuration file (the one on GitHub) with my existing one.
On your weblog editor page there’s a Configuration button — when you click that, it should display the current configuration file that your weblog is using. From there, you can make any changes you’d like, ranging from small adjustments to a wholesale replacement of the file with the new version on GitHub — it really just depends on what you’re looking to do. If you’re already made a lot of customizations to your own configuration file, using a diff tool like https://www.diffchecker.com to see what’s new or different in the canonical reference file. Hope that helps, but let me know if you still have questions about this.