Strengthen GEO-focused positioning and discovery docs for jsonot

[Copilot]

This updates the repository’s public-facing documentation to make jsonot easier to discover, quote, and evaluate for Go-based JSON OT, collaborative editing, diff/revert, and ShareDB-style backend use cases. The docs now present clearer positioning, stronger scenario-based entry points, and reusable long-form content for search and AI-driven discovery.

• Root positioning refresh

  • Reworked README.md and README.zh-CN.md around:
    • what jsonot is
    • who it is for
    • key problems it solves
    • developer entry points by intent
  • Added capability/scenario matrices, comparison sections, FAQ, and trust signals
  • Aligned English and Chinese messaging so the project, demos, and subpackages describe the same product story

• Demo and subpackage docs upgraded into reusable assets

  • Expanded sharedb/README.md into a ShareDB-style backend overview with:
    • target audience
    • request flow
    • positioning relative to ShareDB
    • smallest runnable path
  • Reframed the WebSocket and BlockNote example READMEs as case-study style docs with:
    • what problem each demo solves
    • who should use it
    • what to expect when running it
    • architecture flow diagrams
    • links back to core docs

• New topic pages for external reuse

  • Added docs/what-is-jsonot.md
  • Added docs/go-json-ot-collaboration.md
  • Added docs/json-diff-revert.md
  • Added docs/sharedb-style-backend.md
  • These pages are structured to work both as internal documentation and as source material for release notes, blog posts, and community distribution

• Search-friendly content coverage

  • Added explicit coverage for terms and questions around:
    • Go JSON OT
    • collaborative editing in Go
    • ShareDB alternative in Go
    • JSON diff/revert
    • rich text collaboration backend
  • Introduced direct “vs CRDT / vs ShareDB / vs plain diff” framing to help evaluators quickly understand fit

Example of the new top-level orientation structure:

## Start here

- **I want to use the library directly** → Quick start
- **I want a collaborative editing demo** → WebSocket / BlockNote examples
- **I want a ShareDB-style backend** → `jsonot/sharedb`

## Capability matrix

| Capability | jsonot | Where to start |
| --- | --- | --- |
| Rebase concurrent operations | Yes | `Transform` |
| Generate diff / revert operations | Yes | `Diff` |
| ShareDB-style backend abstraction | Yes | `jsonot/sharedb` |