Add step to request access to dedicated-ase Slack group
Summary
This MR adds documentation for ASEs managing GitLab Dedicated customers to request access to the @dedicated-ase Slack group.
Changes
- Added a new section "Request access to the
@dedicated-aseSlack group" at the end of the customer onboarding documentation - Includes step-by-step instructions for filing an access request using the Slack Request template
- Specifies the required information (group handle, member email, and action type)
- Notes that this is only applicable for ASEs managing Dedicated customers
Related
Closes https://gitlab.com/gitlab-com/team-member-epics/access-requests/-/work_items/40451