Changing CLA to DCO

Author: ryanjbaxter

docs/modules/ROOT/partials/contributing.adoc

@@ -6,15 +6,11 @@ tracker for issues and merging pull requests into main. If you want
 to contribute even something trivial please do not hesitate, but
 follow the guidelines below.
 
-[[sign-the-contributor-license-agreement]]
-== Sign the Contributor License Agreement
-
-Before we accept a non-trivial patch or pull request we will need you to sign the
-https://cla.pivotal.io/sign/spring[Contributor License Agreement].
-Signing the contributor's agreement does not grant anyone commit rights to the main
-repository, but it does mean that we can accept your contributions, and you will get an
-author credit if we do.  Active contributors might be asked to join the core team, and
-given the ability to merge pull requests.
+[[developer-certificate-of-origin]]
+== Developer Certificate of Origin (DCO)
+
+All commits must include a __Signed-off-by__ trailer at the end of each commit message to indicate that the contributor agrees to the Developer Certificate of Origin.
+For additional details, please refer to the blog post https://spring.io/blog/2025/01/06/hello-dco-goodbye-cla-simplifying-contributions-to-spring[Hello DCO, Goodbye CLA: Simplifying Contributions to Spring].
 
 [[code-of-conduct]]
 == Code of Conduct