Updated deprecation of custom hooks from gitlab-shell

data/deprecations/distribution_deprecations_14-4.yml

+- name: "Move `custom_hooks_dir` setting from GitLab Shell to Gitaly" # The name of the feature to be deprecated
+  announcement_milestone: "14.9" # The milestone when this feature was first announced as deprecated.
+  announcement_date: "2021-10-22"
+  removal_milestone: "15.0" # the milestone when this feature is planned to be removed
+  body: | # Do not modify this line, instead modify the lines below.
+    The [`custom_hooks_dir`](https://docs.gitlab.com/ee/administration/server_hooks.html#create-a-global-server-hook-for-all-repositories) setting is now configured in Gitaly, and will be removed from GitLab Shell in GitLab 15.0.

doc/update/deprecations.md

@@ -50,6 +50,12 @@ GitLab self-monitoring gives administrators of self-hosted GitLab instances the
 
 **Planned removal milestone: 15.0 (2022-05-22)**
 
+### Move `custom_hooks_dir` setting from GitLab Shell to Gitaly
+
+The [`custom_hooks_dir`](https://docs.gitlab.com/ee/administration/server_hooks.html#create-a-global-server-hook-for-all-repositories) setting is now configured in Gitaly, and will be removed from GitLab Shell in GitLab 15.0.
+
+**Planned removal milestone: 15.0 ()**
+
 ## 14.8
 
 ### Changes to the `CI_JOB_JWT`