Use describe() to create accessible canvas descriptions in inline documentation

[lm-n]

How would this new feature help increase access to p5.js?

This change from using @alt to using describe() in inline documentation will help model best practices for making p5.js sketches accessible to screen reader users. While @alt creates an extra <span> element after the canvas with the canvas description, describe() follows best accessibility practices (https://developer.mozilla.org/en-US/docs/Web/HTML/Element/canvas) by making the description a fallback text or sub DOM of the <canvas> html element.

Most appropriate sub-area of p5.js?

• Accessibility (Web Accessibility)
• Build tools and processes
• Color
• Core/Environment/Rendering
• Data
• DOM
• Events
• Friendly error system
• Image
• IO (Input/Output)
• Localization
• Math
• Unit Testing
• Typography
• Utilities
• WebGL
• Other (specify if possible)

Feature enhancement details:

• Update EN Contributor Docs
  Update documentation:
• Color Creating and Reading examples
• Color Setting examples
• Shape 2D primitives examples
• Shape Attributes examples
• Shape Curves examples
• Shape Vertex examples
• Shape 3D primitives examples
• Shape 3D models examples
• Constants examples
• Environment examples
• Structure examples
• DOM examples
• Rendering examples
• Foundation examples
• Transform examples
• Data Local Storage examples
• Data Dictionary examples
• Data Array Function examples
• Data Conversion examples
• Data String Functions examples
• Events Acceleration examples
• Events Keyboard examples
• Events Mouse examples
• Events Touch examples
• Image examples
• Image Loading and displaying pixels examples
• IO (Input) examples
• IO (Output) examples
• IO Table examples
• IO Time and Date examples
• Math Calculation examples
• Math Vector examples
• Math Noise examples
• Math Random examples
• Math Trigonometry examples
• Typography Attributes examples
• Typography Loading and Display examples
• Lights Camera - Interaction examples
• Lights Camera - Lights examples
• Lights Camera - Material examples
• Lights Camera - Camera examples

[Qianqianye]

Closing this issue since all the reference docs includes describe() now, with all the documentation PRs merged.