This project is public domain. Any non-trivial contribution (more than 15 lines of code changed) should attach the disclaimer in the WAIVER file to their commit messages so that the intent to release the code into the public domain is clear.
Make sure the waiver is in the COMMIT message, not just the pull request, so that the intent is preserved even if the project is moved to a different git platform.
An even better way to sign your waiver is to gpg --no-version --armor --sign WAIVER and append
that to the AUTHORS file (create it if it doesn't exist)
If you're a company or your employer normally owns the code you write, you should attach a copyright disclaimer signed by your company that releases any copyright interest, such as
Some Company Inc. hereby disclaims all copyright interest in <github.com/Francesco149/baremetal-x86>
signature of Bob Smith 5 June 2020
Bob Smith, President of Some Company