debugger: Update docs with more examples (#31597)

This PR also shows more completion items when defining a debug config in
a `debug.json` file. Mainly when using a pre build task argument.

### Follow ups
- Add docs for Go, JS, PHP
- Add attach docs

Release Notes:

- debugger beta: Show build task completions when editing a debug.json
configuration with a pre build task
- debugger beta: Add Python and Native Code debug config
[examples](https://zed.dev/docs/debugger)

Cargo.lock

@@ -15588,6 +15588,7 @@ dependencies = [
  "futures 0.3.31",
  "gpui",
  "hex",
+ "log",
  "parking_lot",
  "pretty_assertions",
  "proto",