Update LICENSE and reference DCO.

Update copyright to include contributors.
Enforce developer certificate of origin in the
contributing section of the README.

* LICENSE: Update copyright to include contributors.
* README.md (Contributing): Enforce DCO.

Author: real-yfprojects

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2023 real-yfprojects (github.com user)
+Copyright (c) 2023 real-yfprojects (github.com user) and contributors
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

README.md

@@ -231,6 +231,8 @@ Contributions of all kinds are welcome. That explicitely includes suggestions fo
 PRs are greatly appreciated as well. But please make sure that your change is wanted by opening an issue about it first before you waste your time with a PR
 that isn't merged in the end.
 
+By contributing you affirm the [Developer Certificate of Origin](https://developercertificate.org/) and license your work under the terms of this repository.
+
 ## License
 
 MIT License <br>