Linking would be nice.
Indeed, one of the ideas of the guides is that they are top-down/how-to oriented, but are not references. So in general it would be awesome to say: this is how you define and use a has_many, and these are the three most often used options, check the API for the other dozen (linked)". There is no reason this is not actually that way, it is just that nobody did it.
It has to be done with a good taste and balance though, I think it would need some experimentation to see how it would look if applied as a convention throughout the guides. Whatever solution would need to be implemented in a coherent manner.
I mean, it’s something that would impact the guides as a whole and would need to be seen from that global perspective.
It should be done in a way that generates edge or stable links depending on the docs set we are generating.
If you’d like to work on this it would be awesome. I’d only wait a few days, Prem is converting everything to Markdown and merging would not translate the work to the new files.