Update system hooks doc

doc/system_hooks/system_hooks.md

@@ -6,26 +6,27 @@ type: reference
 
 Your GitLab instance can perform HTTP POST requests on the following events:
 
+- `group_create`
+- `group_destroy`
+- `group_rename`
+- `key_create`
+- `key_destroy`
 - `project_create`
 - `project_destroy`
 - `project_rename`
 - `project_transfer`
 - `project_update`
+- `repository_update`
+- `user_add_to_group`
 - `user_add_to_team`
-- `user_remove_from_team`
-- `user_update_for_team`
 - `user_create`
 - `user_destroy`
 - `user_failed_login`
-- `user_rename`
-- `key_create`
-- `key_destroy`
-- `group_create`
-- `group_destroy`
-- `group_rename`
-- `user_add_to_group`
 - `user_remove_from_group`
+- `user_remove_from_team`
+- `user_rename`
 - `user_update_for_group`
+- `user_update_for_team`
 
 The triggers for most of these are self-explanatory, but `project_update` and `project_rename` deserve some clarification: `project_update` is fired any time an attribute of a project is changed (name, description, tags, etc.) *unless* the `path` attribute is also changed. In that case, a `project_rename` is triggered instead (so that, for instance, if all you care about is the repository URL, you can just listen for `project_rename`).