Update debugging.md (--dev -> --save-dev for npm)

[ykdojo]

Reference: https://docs.npmjs.com/specifying-dependencies-and-devdependencies-in-a-package-json-file#adding-dependencies-to-a-packagejson-file-from-the-command-line

Documentation / Examples

• Make sure the linting passes by running pnpm lint
• The examples guidelines are followed from our contributing doc

[styfle]

Let’s use -D for both yarn and npm