The developer API product and only the developer API product needs to be documented to fulfill this rock. This requires:
The product owners (PM) to definitively determine what portions of the codebase are part of the developer API product & what is the rest of the platform.
Reference docs must be auto-generated for the entire developer API product.
Code examples for all portions of the developer API product must be linked from the relevant sections of the docs site. Code examples can be a mix of inline examples on the docs site, links to relevant lines of contracts or sample dapps.