Restructure README documentation sections

[Copilot]

README restructuring to separate origins from description and improve section ordering.

Changes

• New "Origins" section (before License): Documents expr-eval 2.0.2 lineage, modular architecture rewrite, TypeScript/Vitest adoption, and expanded scope beyond mathematical expressions
• Updated "Description" section: Refocused on library's versatility for strings, objects, and arrays rather than just math
• Moved "Playground Example": Now above "Documentation" section for better discoverability

Original prompt

1. Create a documentation section named "Origins" that explains:
   That the library was originally based on expr-eval 2.0.2, butn has been restructured with a modular architecture, TypeScript support, and comprehensive testing using Vitest.
   That expr-eval was only focused on mathemacial expressions where this library aims at being a tool to evaluate expressions that can manipulate string, objects and arrays.
   Put it on the bottom, just before the license section.

2. Create a new "Description" section

3. Move the Playground Example section above the Documentations section

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[Copilot]

Pull request overview

Restructures the README to better separate project background from the main description and improve section ordering for discoverability.

Changes:

• Refocuses the Description section on broader expression capabilities (strings/objects/arrays), not just math.
• Moves Playground Example above Documentation.
• Adds a new Origins section near the end (before License) describing lineage and modernization.

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[Copilot]

The updated README description says the library goes beyond mathematical expressions (strings/objects/arrays), but the published docs still frame it as a mathematical expression evaluator (e.g., docs/index.md:5 and docs/index.md:11). This creates conflicting messaging for users. Consider updating the docs’ intro/tagline to match this new positioning, or rewording the README description to stay consistent with the existing docs until those are updated.

Suggested change

	A versatile expression evaluation library that goes beyond mathematical expressions. It parses and evaluates expressions that can manipulate strings, objects, and arrays, providing a safer alternative to JavaScript's `eval` function.
	A mathematical expression evaluation library for JavaScript. It parses and evaluates expressions with support for numbers, strings, objects, and arrays, providing a safer alternative to JavaScript's `eval` function.