Revise What's New for inferring compression from non-string paths
This pull request improves the What's New message corresponding to https://github.com/pandas-dev/pandas/pull/17206, which updated `io.common._infer_compression` to infer compression from non-string paths.

Refs https://github.com/pandas-dev/pandas/issues/17262
Refs https://github.com/pandas-dev/pandas/pull/17206#issuecomment-322586996