gh-125904: Fix and simplify "Multiple Inheritance" section in Tutorial #139999
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I'm continuing work of @drewarnett for #125904. It took a while to me to unterstand that we have an issue in tutorial. I'd say current description is misleading. We need to fix it.
Also, I've seen a request from @erlend-aasland to simplify entire section. I agree. So I replaced heavy explanation for MRO with simple examples and kept a link to
python_2.3_mrofor curious readers.For the reference two pull requests were originally created, but closed:
📚 Documentation preview 📚: https://cpython-previews--139999.org.readthedocs.build/