Readme.Rs Third Party License Review

Quick note how to review license-related changes in readme.rs

For changes that add support for a new license kind, please follow the process described in the "License" section of //docs/adding_to_third_party.md. An old revision of that doc here asks to check if the new license has been allowlisted in a depot_tools script. That old revision also listed license kinds that should be allowed in Chromium (e.g. permissive licenses or reciprocal licenses) - whether a license is classified as permissive or reciprocal can be checked in the internal go/licensetable.

For benign changes (e.g. adding a new free-form spelling of "MIT or Apache-2") there is no need for any additional review.