Create `architecture` section of docs to talk about common design patterns

[davidthor]

Architect is designed to help developers with common cloud architectural patterns, but we don't have any docs highlighting how you'd use those patterns specifically. This would be a lot like "guides", but would be higher level. Given our product name, this likely warrants its own category in the docs.

• Create new "architecture" sidebar category
• Create doc for full-stack applications
• Create doc for microservices
• Create doc for event-driven architecture

Any other docs will be logged in a different ticket.