Revert documentation to Jekyll
Previously, we used Jekyll as our tool for hosting the GNOME UI library documentation. Jekyll is easier for the current contributors to maintain and was already looking better with the chosen theme.
This was the last state of the repository that was using Jekyll, it can be used as a reference.
It's important that the documentation that was written after the migration to Hugo gets migrated as well.
Out of bonds
The dump for the Tailwind documentation is not necessary at this point and will be discussed in another issue.