Mention this is closed source downstream

[LirionOSS]

Nowhere in the docs has it been mentioned that this repository (and probably others too) have moved to a closed-source-first approach and this is only a delayed downstream, which is already confusing people.

Please adapt: Write this down prominently in the main Readme and/or archive this project, the latter if this continues to receiving no updates.

[kenyon]

The replacement: https://github.com/OpenVoxProject/puppet