[#4907] Improve developer installation documentation #14821

Job	Run time
Build and check documentation	3m 58s
Set up docker build 'dynamic' env variables	1s
End-to-end tests, chromium	13m 48s
End-to-end tests, firefox	16m 43s
End-to-end tests, webkit	11m 55s
Run the Django test suite	8m 15s
Run the Django test suite in reverse	5m 14s
docker_build (extensions, token_exchange,prefill_haalcentraalhr, all-extensions-) / Build image	2m 45s
docker_build (production) / Build image	2m 47s
Scan docker image	2m 5s
Simulate upgrading instances (2.7.4)	1m 30s
Simulate upgrading instances (2.7.8)	1m 29s
Check for unexepected OAS changes	3s
Generate SDKs from OAS	33s
Generate Postman collection from OAS	23s
Validate OAS	12s
Push Docker image	0s
update-docker-readme	0s
	1h 11m 41s

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