replace obsolete platforms with more recent examples

[partev]

replace two examples:

• linux-i586
• linux-alpha (?)

that are almost never used nowadays with the two most common Linux architectures (x86_64 and ARM64)

• linux-x86_64
• linux-aarch64

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📚 Documentation preview 📚: https://cpython-previews--132455.org.readthedocs.build/en/132455/library/sysconfig.html#sysconfig.get_platform

[StanFromIreland]

This is just a cosmetic change IMO, the examples are not wrong.

[ZeroIntensity]

I think this makes sense.

Cosmetic changes generally refer to cosmetic code changes, not documentation.

[FFY00]

Thanks @partev!

[FFY00]

Droping the sysconfig changes as they have already been updated.