Fix crate urls in README.md

[kokjo]

Summary of the PR

Crate urls in README.md pointed to vfio-ioctl which is an archived repository.

Requirements

Before submitting your PR, please make sure you addressed the following requirements:

• [x] All commits in this PR have Signed-Off-By trailers (with git commit -s), and the commit message has max 60 characters for the summary and max 75 characters for each description line.
• [x] All added/changed functionality has a corresponding unit/integration test.
• [x] All added/changed public-facing functionality has entries in the "Upcoming Release" section of CHANGELOG.md (if no such section exists, please create one).
• [x] Any newly added unsafe code is properly documented.

[kokjo]

Could you please add a body to your commit message? Otherwise the content of the patch LGTM

Done!