docs: fix broken link to the license file

[vil02]

Description

Related to #154.

Fixes the link to the license. Please notice that I decided to leave the absolute path. I am not sure what it the legal point of view, but it somehow makes sense that each fork and branch is under the same license.

Checklist

• A description of the changes in this PR is mentioned above.
• All the new and existing checks pass.
• No plagiarized, duplicated, or repetitive documentation that has been directly copied from another source.
• If it's a new explanation, it contains solid, understandable, and accessible information.
• I have read the whole contributing guidelines and agree to the Code of Conduct.

Screenshots (if any)

Note to reviewers

[appgurueu]

I think a relative path would make slightly more sense though (say someone clones or forks this). If we were to change our license, or if the forking person was to change the license (of course in a compatible manner) that should not cause any issues.