Add Korean translation for WebGPU contributor guide

[eupthere]

Increasing access

It would help Korean contributors understand the goals and aspiration of WebGPU on p5.js.

Most appropriate sub-area of p5.js?

• Accessibility
• Color
• Core/Environment/Rendering
• Data
• DOM
• Events
• Image
• IO
• Math
• Typography
• Utilities
• WebGL
• Build process
• Unit testing
• Internationalization
• Friendly errors
• Other (specify if possible)

Feature request details

Add contributor_docs/ko/webgpu.md document.