Clarify how to contribute to this repo

[remyjette]

The "Contributing" section of README.md states that this "This project welcomes contributions and suggestions"

However, nearly every file in azure-devops/azure/devops states

# Generated file, DO NOT EDIT
# Changes may cause incorrect behavior and will be lost if the code is regenerated.

It is unclear what the correct process is to propose changes, as well as how to regenerate these files.