[en] update kubernetes link

Author: Arhell

content/en/docs/contribute/participate/_index.md

@@ -93,7 +93,7 @@ and editorial review of their PR.
 
 ## How merging works
 
-When a pull request is merged to the branch used to publish content, that content is published to http://kubernetes.io. To ensure that
+When a pull request is merged to the branch used to publish content, that content is published to https://kubernetes.io. To ensure that
 the quality of our published content is high, we limit merging pull requests to
 SIG Docs approvers. Here's how it works.