Update custom hooks docs and set 4.1.0

GITLAB_SHELL_VERSION

-4.0.3
+4.1.0

doc/administration/custom_hooks.md

@@ -44,22 +44,30 @@ as appropriate.
 
 ## Chained hooks support
 
-> [Introduced][93] in GitLab Shell 4.1.0.
+> [Introduced][93] in GitLab Shell 4.1.0 and GitLab 8.15.
 
-The hooks could be also placed in `hooks/<hook_name>.d` (global) or `custom_hooks/<hook_name>.d` (per project)
-directories supporting chained execution of the hooks.
+Hooks can be also placed in `hooks/<hook_name>.d` (global) or
+`custom_hooks/<hook_name>.d` (per project) directories supporting chained
+execution of the hooks.
+
+To look in a different directory for the global custom hooks (those in
+`hooks/<hook_name.d>`), set `custom_hooks_dir` in gitlab-shell config. For
+Omnibus installations, this can be set in `gitlab.rb`; and in source
+installations, this can be set in `gitlab-shell/config.yml`.
 
 The hooks are searched and executed in this order:
+
 1. `<project>.git/hooks/` - symlink to `gitlab-shell/hooks` global dir
 1. `<project>.git/hooks/<hook_name>` -  executed by `git` itself, this is `gitlab-shell/hooks/<hook_name>`
 1. `<project>.git/custom_hooks/<hook_name>` - per project hook (this is already existing behavior)
 1. `<project>.git/custom_hooks/<hook_name>.d/*` - per project hooks
-1. `<project>.git/hooks/<hook_name>.d/*` - global hooks: all executable files (minus editor backup files)
+1. `<project>.git/hooks/<hook_name>.d/*` OR `<custom_hooks_dir>/<hook_name.d>/*` - global hooks: all executable files (minus editor backup files)
 
-Files in `.d` directories need to be executable and not match the backup file pattern (`*~`).
+Files in `.d` directories need to be executable and not match the backup file
+pattern (`*~`).
 
-The hooks of the same type are executed in order and execution stops on the first
-script exiting with non-zero value.
+The hooks of the same type are executed in order and execution stops on the
+first script exiting with a non-zero value.
 
 ## Custom error messages
 

doc/update/8.14-to-8.15.md

@@ -72,7 +72,7 @@ sudo -u git -H git checkout 8-15-stable-ee
 ```bash
 cd /home/git/gitlab-shell
 sudo -u git -H git fetch --all --tags
-sudo -u git -H git checkout v4.0.3
+sudo -u git -H git checkout v4.1.0
 ```
 
 ### 6. Update gitlab-workhorse