Doc statement about minimum abi3 version is wrong

[bschoenmaeckers]

https://pyo3.rs/v0.14.5/building_and_distribution#minimum-python-version-for-abi3

Note: If you set more that one of these api version feature flags the highest version always wins. For example, with both abi3-py36 and abi3-py38 set, PyO3 would build a wheel which supports Python 3.8 and up.

The docs state that the highest abi3 version will win. But pyo3-build-config selects the lowest one.

https://github.com/PyO3/pyo3/blob/059e249057e895cfa36504890dfa79943f0b49c5/pyo3-build-config/src/impl_.rs#L854-L858

Secondly the lower abi3 feature flags enable the higher ones as well so setting a higher flag will be essentially a no-op if their is a lower one present.

https://github.com/PyO3/pyo3/blob/059e249057e895cfa36504890dfa79943f0b49c5/Cargo.toml#L97-L103

I would like to use the (wrongly stated) feature to dynamically build higher abi3 wheels with maturin build --features pyo3/abi3_py312 but leave the default feature set compatible with abi3_py39. Is it possible to make this work or should we update the docs that this is not possible?