docs: Add instructions on how to add new functionality #274

Job	Run time
format_code / fmt	11s
build_dev_container / build_dev_container	1m 16s
integration_test / test	4m 48s
unit_test / test	4m 59s
lint / lint	4m 24s
build / build	5m 44s
build_release_image / build	24s
	21m 46s

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