[docs] Fix suggestion for index strategy (#12634)

## Summary

Fix a suggestion in the docs on configs through environment variables,
which lists an option value that doesn't appear to exist.
The description implies that `unsafe-best-match` was intended here.

## Test Plan

Verified by providing `unsafe-any-match` as a parameter to `uv`. It
didn't error, but appeared to use the `first-index` strategy instead.
The value I changed it to behaves as described by the documentation.

Add `UV_PROJECT` to changelog (#12563)

Bump version to v0.6.10 (#12430)

Bump version to 0.6.9 (#12347)

Bump version to 0.6.8 (#12297)

Allow dirty files in `cargo-dist` for action pins (#12252)

Bump version to 0.6.6 (#12125)

Bump version to 0.6.5 (#12018)

Explicitly install the rust toolchain before the target during Docker…

… builds (#11936)

Fixes
https://github.com/astral-sh/uv/actions/runs/13641331357/job/38131724427

Bump version to 0.6.3 (#11759)