First pre-release for testing

To make a first pre-release of HDO and test the release pipeline, we will have to do the following:

• Add text to the top-level README.Md that the release artifact is experimental and should not be used unadvisedly
• Add an annotation property to the ontology itself that the release artifact is experimental and should not be used unadvisedly
• Fix / clean-up the import chain as described in #20 (closed) @pier.buttigieg to work with @s.fathalla
• Delete all .bak files - these are not necessary and, according to the OBO Community, likely unintended artifacts of the ODK.
• Set up a Helmholtz HOB server with 4-8 CPUs, 32 GB RAM, access to the web, and SSH access for editors to run the ODK container (requires docker). Ubuntu architecture is fine.

We'll add a GitLab action to run QA/QC shortly after this pre-release.