Updated README.md to replace a dead link

[IoanCroitor]

Summary:
Updated Rust Style Guide dead link.

• Issue:
  This pull request addresses the issue of a broken link that currently leads to a 404 page. It replaces the broken link with the correct updated location.

• Proposed Changes:

  • Replace the broken link: https://github.com/rust-lang/style-team/blob/main/guide/guide.md
  • With the updated location: https://github.com/rust-lang/rust/tree/master/src/doc/style-guide/src

By submitting this pull request, I promise I have read the contribution guidelines twice and ensured my submission follows it. I realize not doing so wastes the maintainers' time that they could have spent making the world better. 🖖