ADR-26: Open the repos

[cornelius]

This ADR is meant to record the decision of what exactly to open with opening the repositories so that we are all on the same page. See the text of the ADR for details.

It depends on a couple of other pull requests which bring the repos into a publishable shape. These are:

• [x] https://github.com/dtr-org/unit-e/pull/913
• [x] https://github.com/dtr-org/uips/pull/17
• [x] https://github.com/dtr-org/unit-e-clonemachine/pull/32
• [x] https://github.com/dtr-org/docs.unit-e.io/pull/25
• [x] https://github.com/dtr-org/docs.unit-e.io/pull/24
• [x] https://github.com/dtr-org/unit-e-project/pull/112

They are mostly small adjustments.

With them we have reached a state which, from my point view, is nice, consistent, and ready for being published. There certainly is still more work to do and we will improve things over time, but this can happen in the open.

I'm creating this PR as a draft for now because of the pending reviews of the other pull requests it depends on. Once these are reviewed we can promote it to ready for review. The text of the ADR can already be reviewed now, though.

This closes #21.

[frolosofsky]

ACK 70a2b6b271dc34d6d939d608f104faef100acb0f

[cornelius]

Merging this now as we have approval from everybody.

Actual opening of the repos is tracked in https://github.com/dtr-org/unit-e-project/issues/66