Add KDL Language

[TheLostLambda]

Language name

KDL: https://kdl.dev/

URL of example repository

https://github.com/kdl-org/kdl

URL of syntax highlighting grammar

Grammar Spec: https://github.com/kdl-org/kdl/blob/main/SPEC.md
Implementation: https://github.com/tree-sitter-grammars/tree-sitter-kdl

Most popular extensions

Just .kdl currently

Detected language

Not currently detected, as far as I can tell!

Other

I'm low on time, otherwise I'd try to submit the PR myself! If some others have the time, please give it a go!