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## Summary
Update this example snippet adding test.pypi.org as a publishing index
to mark the index with `explicit = true`. This will help prevent users
from unexpected behavior if no other indices are defined and users don't
select a different index selection algorithm (with `--index-strategy`).
When `test.pypi.org` is the selected index for package management,
packages resolve to odd versions like 0.0.1 and `uv` spits out lots of
errors.
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## Test Plan
N/A, documentation only change
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