Update Invitations API page based on initial review
This page describes product documentation work that was identified during a documentation review of documentation pages associated with the Growth:Expansion stage/group.
- What subscription levels have access?
- Can we cross-link with the UI version of inviting users?
- Cross-link https://docs.gitlab.com/ee/api/invitations.html#valid-access-levels to permissions
- Needs punctuation in tables
- Pedantry alert: https://docs.gitlab.com/ee/api/invitations.html#delete-an-invitation-to-a-group-or-project use the real name of the HTTP response, and wrap it in code tags
- Missing from left nav. gitlab-docs!1577 (merged)