[WIP] Document CSR end-to-end tests environment setup

[Copilot]

Cloud agent has begun work on I need to understand... and will update this pull request as work progresses.

Original prompt

I need to understand what is this file, how it used in this repo and how I can use it as a reference for same task (setup environment for CSR e2e tests) in deferent repo (ex.: https://github.com/maximsemenov80/azure-iot-sdk-c/tree/feature/dps-csr-preview) use diagrams for illustrations.

The user has attached the following file paths as relevant context:

• vsts/dps-e2e-cert-mgmt.yaml

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