Define requirements for release process

[cornelius]

We had a discussion about requirements for the release process of OpenRail projects. This was mostly about signing release artifacts. Another aspect we discussed before was versioning.

We should write these requirements down as part of the project handbook. There probably is no one-size-fits-all solution, but at least documenting best practices would be helpful.

In the incubation process we can then reference these best practices and discuss if we want to make certain practices mandatory for the more mature stages of the incubation.

[cornelius]

One example of a documented release process: https://doc.rust-lang.org/book/appendix-07-nightly-rust.html