docs: add a draft outline to explore how to improve our documentation site

[raymondfeng]

Please review https://github.com/strongloop/loopback-next/blob/docs-improvement/docs/site/Site-improvement.md.

Checklist

👉 Read and sign the CLA (Contributor License Agreement) 👈

• npm test passes on your machine
• New tests added or existing tests modified to cover all changes
• Code conforms with the style guide
• API Documentation in code was updated
• Documentation in /docs/site was updated
• Affected artifact templates in packages/cli were updated
• Affected example projects in examples/* were updated

👉 Check out how to submit a PR 👈

[dhmlau]

@raymondfeng, your proposal LGTM.
+1 on the separation of the high-level overview and deep-dive topics.

Capturing our discussion, I had a question about where the topics around the data layer would fit in. You mentioned there could be an extra section about "Data and service integration".

[kowsheek]

Further to the topics outlined, I'd propose a design update too, making the doc site more accessible. Drawing comparison to TypeScript or Nest and even the LB4 home site, there's a lack of UX on the doc site.

[raymondfeng]

The proposal has been incorporated into #3164.