Add React compatible example to p5() instance method

Increasing Access

Unsure
Although it may not have an immediate impact on increasing access to people listed in the documentation, it will help anyone trying to use p5js in a React application.

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
• Internalization
• Friendly Errors
• Other (specify if possible)

Feature enhancement details

I want to provide two examples of using the p5() instance method to render sketches in a React project. The first will utilize the existing example in a React project context. The second will be more advanced: I will provide an example of how to expose the parameters of a p5 sketch to the client using a closure.

Start with the existing p5() instance-method example and the documentation context; no file or test is named in the issue. Add two React examples: one adapting the existing example and one showing closure-based parameter exposure, then confirm both examples are understandable and render as intended.