We now have an easier way to get at the language-specific configuration
in Rust, since we publish each language grammar as a crate with useful
accessor functions and globals.
* Correct README.md in /highlight
correct the lifetime in highlighter.highlight and correct the cases in match so that the demo in README could work.
* Update README.md
another small fix
* Update highlight/README.md
Co-Authored-By: Max Brunsfeld <maxbrunsfeld@github.com>