CTRT: SAML SSO for GitLab.com groups

Problem to solve

Implement CTRT format on https://docs.gitlab.com/ee/user/group/saml_sso/index.html.

Bring the content in the SAML SSO for GitLab.com groups in line with best practice.

Part of FY24Q1 TW OKR: Refactor high visibility pages for improved content design and better scannability.

Will introduce individual MRs with:

## What does this MR do?

Implement CTRT format on existing content in [SAML SSO for GitLab.com groups](https://docs.gitlab.com/ee/user/group/saml_sso/index.html). Specifically:

- X
- Y
- Z

This MR is one of multiple MRs to implement CTRT on this page.

## Related issues

https://gitlab.com/gitlab-org/gitlab/-/issues/390688
https://gitlab.com/gitlab-org/technical-writing/-/issues/749

Further details

Use same approach as #384052 (closed).

Proposal

Who can address the issue

Technical writer.

Other links/references