The documentation that you outline mixes (conflates) four distinct kinds of documentation (https://documentation.divio.com/). As does Matlab’s system. In many ways this is suboptimal. Perhaps here may Julia also lead the way as it does in language design. However, it needs to be recognized that this represents a major effort. Ever wonder what all those people at Mathworks actually do?
Looks my comment lost out to @jar1 who got it in first.