docs: Add instructions on how to add new functionality #260

Job	Run time
format_code / fmt	3s
build_dev_container / build_dev_container	1m 16s
unit_test / test	4m 56s
build / build	6m 26s
lint / lint	4m 26s
integration_test / test	5m 11s
build_release_image / build	33s
	22m 51s

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