Refresh product pages

[pauldougan]

What

Based on input from the product managers and tech arch we have extended to product documentation to incorporate material that had only been available to prospective tenants in the primer document.

changes as follows:

• restructured features page
• new developer page
• new observability page
• new constraints page

How to review

• pull the branch
• run the app locally
• ensure essential wiring of pages works
• review content for inaccuracies and plain english

Who can review

• a product manager
• someone from the technical team

[pauldougan]

@markpeterbuckley lets take a look at the roadmap whilst we are making these changes so its consistent

[markpeterbuckley]

Reviewed with Paul and incorporated feedback.