## Summary

Adds three syntax highlighting captures that are used across multiple
language definitions but were missing from the documentation table in
`docs/src/extensions/languages.md`.

## Added Captures

| Capture | Used In |
|---------|---------|
| `@constant.builtin` | C, Go, C++, YAML, TSX |
| `@type.builtin` | C++, Python, Rust, JavaScript, TSX |
| `@variable.parameter` | TypeScript, JavaScript, Python, Rust, TSX,
Diff |

## Context

While working on a [PR to add named argument highlighting to the PHP
extension](https://github.com/zed-extensions/php/pull/95), I initially
used `@label` because the documentation didn't list
`@variable.parameter`. A reviewer pointed out that `@variable.parameter`
is actually supported and preferred - the docs were just outdated.

This PR fixes that documentation gap.

Release Notes:

- N/A