[DOC][Workspace] Add documentation for workspace UX and API

[ruanyl]

What do you want to do?

• [ ] Request a change to existing documentation
• [x] Add new documentation
• [ ] Report a technical problem with the documentation
• [ ] Other

Tell us about your request. Provide a summary of the request and all versions that are affected.

What other resources are available? Provide links to related issues, POCs, steps for testing, etc.

[hdhalter]

Hi @ruanyl , is this a feature being implemented in an upcoming release?

[xluo-aws]

Please reassign to @SuZhou-Joe

[vagimeli]

@SuZhou-Joe Please tag me when the initial draft content PR is ready for tech writer support and review. Thank you.