Unsafe design guidelines

[pawelrutkaq]

Provide unsafe design guidelines for developers. Contribute to https://google.github.io/learn_unsafe_rust/ and also bring this document into S-CORE documentation.

[dcalavrezo-qorix]

Hi @pawelrutkaq,

Is this issue still relevant? If not, please add the trash label so it can be marked for deletion.

[dcalavrezo-qorix]

check rust-lang/rust-project-goals#511

[AlexanderLanin]

design guidelines are not in INF, no idea why github added it to INF