Add the language transpiler written in

It would be nice if we know what the language the transpiler written in the main readme, instead of clicking one by one to find what it was.

e.g. I want to find transpiler that written in C instead of Rust.

Start with the main README and inspect how the compiler entries are currently listed. Add the language each transpiler is written in, including enough information for readers to identify C- and Rust-written transpilers without opening entries one by one. Done means the README exposes this information consistently for the listed transpilers.

Written by the indexing model from the issue text.