Add JSDoc for Parser module

[MajorLift]

As part of our initiative to overhaul documentation for this library, we need JSDoc comments to be written for the following Object module methods, so that they can be automatically published using TypeDoc and GitHub Pages.

• Choice
• Letter
• Letters
• Many1
• Map
• ObjectSequence
• Optional
• Parser
• Run
• Sequence
• State
• String
• TakeSequence

The JSDoc comments must adhere to the guidelines laid out in style-guide/jsdoc.md.

Here are two previous examples where the style guide was fed to an AI assistant to successfully generate documentation in JSDoc format.

• JSDoc: String Module #60
• Add JSDoc for List utilities #56