Document using markers with different sources

[ethiy]

• I have searched the issues of this repo and believe that this is not a duplicate.

Issue

It is not clear how to use markers to make an project usable across different platforms and architectures.(cf. issue #7337).

It would be beneficial to add a section or a use case where one can use different repositories for different cases.

[dimbleby]

https://python-poetry.org/docs/dependency-specification#using-environment-markers

I expect if you have specific improvements in mind then a merge request would be welcomed

[neersighted]

Different repositories for different architectures is a bit of an anti-pattern, and something that I would say we're not looking to encourage in the ecosystem in general, not in the least because Poetry supports it better than other tools, but Poetry's support is also maturing and exposing bugs in the solver.

Generally, the idiomatic thing to do here would be using a proxying repository and uploading additional wheels yourself, or using multiple backing sources. The general solution in Python packaging has been, and will continue to be, "run your own index infrastructure."

That being said, docs improvements are of course welcome. Just keep in mind that anything highly specific to a marginal/discouraged use case will likely need to be generalized, and we don't want to promote it over the blessed/cross-tool solution of custom indexes.