Remove outdated collaboration doc

The contents of collab.md are out of date and the intent of the document
is better captured in some of the other docs such as expectations.md[1],
pull-requests.md[2] and review-guidelines.md[3].

[1] https://git.k8s.io/community/contributors/guide/expectations.md
[2] https://git.k8s.io/community/contributors/guide/pull-requests.md
[3] https://git.k8s.io/community/contributors/guide/review-guidelines.md

Author: mrbobbytables

community-membership.md

@@ -227,7 +227,7 @@ The following apply to the subproject for which one would be an owner.
 
 The Maintainer role has been removed and replaced with a greater focus on [OWNERS].
 
-[code reviews]: /contributors/guide/collab.md
+[code reviews]: /contributors/guide/expectations.md#code-review
 [community expectations]: /contributors/guide/expectations.md
 [contributor guide]: /contributors/guide/README.md
 [Kubernetes GitHub Admin team]: /github-management/README.md#github-administration-team