Add tutorial blog posts to workspaces docs

What does this MR do?

Dev Evangelism and Technical Marketing teams created tutorial blog posts for remote development workspaces. In the first iteration, we can add the resources into the GitLab documentation as shortened URLs (tracking our KPI metrics).

This MR creates a new section Tutorials and Demos to keep the existing demo URL. The section is added on top.

This MR is a boring solution until we refactor the documentation for remote development and workspaces in #411516 (closed) cc @oregand @ericschurter

FYI @gitlab-de

Related issues

• #411516 (closed)

Author's checklist

• Optional. Consider taking the GitLab Technical Writing Fundamentals course.
• Follow the:
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  • Style Guide.
• If you're adding or changing the main heading of the page (H1), ensure that the product tier badge is added.
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If you are a GitLab team member and only adding documentation, do not add any of the following labels:

• ~"frontend"
• ~"backend"
• ~"type::bug"
• ~"database"

These labels cause the MR to be added to code verification QA issues.

Reviewer's checklist

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• If the content requires it, ensure the information is reviewed by a subject matter expert.
• Technical writer review items:
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  • Ensure a release milestone is set.
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