license this repo under the MIT license

All previous contributors are asked to sign off on licensing this repo
under the MIT license in PR 12
(CCCHH/nix-infra#12). Once all
contributors signed-off, this commit will be merged into the main
branch and this repo will be licensed under the MIT license.

Don't track copyright years in the license, as that is cumbersome and
also not done in other projects anymore:
https://daniel.haxx.se/blog/2023/01/08/copyright-without-years/
https://github.com/rails/rails/pull/47467

MIT License:
https://opensource.org/license/MIT
https://choosealicense.com/licenses/mit/

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) CCCHH
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -73,3 +73,7 @@ Build a new NixOS Proxmox VE Template for the chaosknoten:
 ```shell
 nix build .#proxmox-chaosknoten-nixos-template
 ```
+
+## License
+
+This CCCHH nix-infra repository is licensed under the [MIT License](./LICENSE).