docs: Document what happens under the hood when someone applies a promise or resource request

[catmo-syntasso]

Context

We've been asked recently by customers who are getting deeper into Kratix learning for information about what happens when people request things of Kratix, and what happens under the hood.
Customer quote below:

We are currently looking a bit deeper into what happens in the background when someone orders a resource - Is there a technical documentation (e.g. Flowchart) available about which resources (e.g. Pods, Jobs, Workplacements, ...) are created at which time inside Kubernetes?

We should document this flow and add it to our promise and resource reference pages

Done when

• Document what happens when someone applies a promise (Both external and Kratix internals)
  • With a diagram process flow
• Document what happens when someone requests a resource (both external and kratix internals)
  • With a diagram process flow