feat: add DA prefix doc

[maheshwarishikha]

Description

Adds a new section Deployable Architecture authoring guidelines that includes prefix variable related information.

Release required?

• No release
• Patch release (x.x.X)
• Minor release (x.X.x)
• Major release (X.x.x)

Release notes content

Adds a new section Deployable Architecture authoring guidelines.

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Run the CI pipeline when the PR is ready for review and you expect tests to pass. Add a comment to the PR with the following text:

/run pipeline

Checklist for reviewers

• If relevant, a test for the change is included or updated with this PR.
• If relevant, documentation for the change is included or updated with this PR.

For mergers

• Use a conventional commit message to set the release level. Follow the guidelines.
• Include information that users need to know about the PR in the commit message. The commit message becomes part of the GitHub release notes.
• Use the Squash and merge option.

[ocofaigh]

See comments. Also to get it to show in GH pages, you need to add it to docs/_sidebar.md