Enhance Workspaces setup for GitLab UI

With chore: Fix workspaces setup in GitLab UI (gitlab-ui!5023 - merged) (Thanks @ealcantara!) the GitLab UI is Workspaces ready for contributors.

We also have some documentation here https://gitlab.com/gitlab-org/gitlab-ui/-/blob/main/doc/contributing/workspaces.md for users to reference.

The purpose of this issue is to enhance and amplify that. Particularly cause we have other tools like Gitpod mentioned here https://gitlab.com/gitlab-org/gitlab-ui/-/tree/main?ref_type=heads#quick-start---development in the root readme of the project.

Acceptance Criteria

• The GitLab UI root README is updated to mention GitLab Workspaces as a development environment
• The documentation in doc/contributing/workspaces.md is linked or referenced in the README to guide users on setting up Workspaces.
• TBD on making our setup competitive. See note: #525561 (comment 2403795360).
• TBD on more messaging options to increase reach