Update documentation for invite members group modal
We need to update - and possibly add new - documentation to highlight there is a feature flag that when enabled provides a different way to invite users to groups and projects, and to share project and groups with groups.
Feature flag Rollout issue and screenshots: #247208
Changes to consider:
- Invite users to a project: https://docs.gitlab.com/ee/user/project/members/#invite-people-using-their-e-mail-address
- Share project with a group: https://docs.gitlab.com/ee/user/project/members/share_project_with_groups.html
- Invite users to a group: https://docs.gitlab.com/ee/user/group/subgroups/#membership
- Share group with a group: https://docs.gitlab.com/ee/user/group/#share-a-group-with-another-group
- API changes are not behind this feature flag and are covered in #18464 (closed)
Walk through of the UI changes: https://youtu.be/f3YLenMGSqg
MVC is to ensure the 4 pages listed above include the feature flag message, and a (one line) description of the change. Something like (pseudo-markdown):
> ### Invite Members Modal > > - [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/247208) in GitLab 13.10. > - It's [deployed behind a feature flag](../../feature_flags.md), disabled by default. > - It's enabled on GitLab.com. > - It's recommended for production use. > - For GitLab self-managed instances, ask a GitLab administrator to enable the `invite_members_group_modal` feature. > > When this feature flag is enabled the existing form is replaced with a modal.
Replaces form with button and modal: #247208
Further changes to these docs - including screenshots - can be considered when this feature is enabled by default (13.11 at the earliest).