This is not a full portage configuration. It contains only those parts that are necessary to set up a gentoo github mirror based sync system:

• Configures Portage to sync via https://github.com/gentoo/gentoo.git URL.
• Updates metadata-cache.
• Updates the dtd directory.
• Updates the glsa directory.
• Updates projects.xml file
• Updates the news directory.

If you want your overlay metadata caches to be automatically regenerated as well, do:

chmod +x /etc/portage/repo.postsync.d/sync_overlay_cache