Defining definition files with a 3-character extension causes the pipeline to hang

[wilson1000]

Real-world context
Definition files are considered correctly named when defined as: 00-network.yml

System context
Automated services do not permit 3-character extensions.

Impact
Without the 4-character extension, the impact is fatal. The pipeline fails and services are not created.

Suggested remedy
The distinction should be declared clearly in the documentation:
https://user-guide.cloud-platform.service.justice.gov.uk/documentation/reference/namespace-definition-files.html#kubernetes-namespace-definition-files