docs: clean up CONTRIBUTING.md and other docs

[aaronsteers]

Clean up CONTRIBUTING.md, README.md. Delete TESTING.md and considate with CONTRIBUTING.md.

Note:

• These files got bloated due to mainly being written by Devin.

[github-actions]

👋 Greetings, Airbyte Team Member!

Here are some helpful tips and reminders for your convenience.

Testing This Branch via MCP

To test the changes in this specific branch with an MCP client like Claude Desktop, use the following configuration:

{
  "mcpServers": {
    "connector-builder-mcp-dev": {
      "command": "uvx",
      "args": ["--from", "git+https://github.com/airbytehq/connector-builder-mcp.git@aj/docs/clean-up-contributing-md", "connector-builder-mcp"]
    }
  }
}

Testing This Branch via CLI

You can test this version of the MCP Server using the following CLI snippet:

# Run the CLI from this branch:
uvx 'git+https://github.com/airbytehq/connector-builder-mcp.git@aj/docs/clean-up-contributing-md#egg=airbyte-connector-builder-mcp' --help

PR Slash Commands

Airbyte Maintainers can execute the following slash commands on your PR:

• /autofix - Fixes most formatting and linting issues
• /poe <command> - Runs any poe command in the uv virtual environment
• /poe build-connector prompt="Star Wars API" - Run the connector builder using the Star Wars API.

📝 Edit this welcome message.

[Copilot]

Pull Request Overview

This PR restructures the documentation by moving detailed testing instructions from CONTRIBUTING.md to a dedicated TESTING.md file and streamlining the README.md with simplified quick start information.

• Comprehensive testing guide extracted to TESTING.md with detailed FastMCP CLI examples
• CONTRIBUTING.md reorganized to focus on development setup and MCP tool development
• README.md simplified by removing redundant quick start sections

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
TESTING.md	New comprehensive testing guide with FastMCP CLI tools, testing patterns, and debugging instructions
README.md	Simplified by removing detailed quick start and Poe task sections, focusing on MCP client configuration
CONTRIBUTING.md	Restructured to focus on development setup, MCP tool development patterns, and debugging

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[github-actions]

PyTest Results (Fast)

0 tests  ±0   0 ✅ ±0   0s ⏱️ ±0s
0 suites ±0   0 💤 ±0 
0 files   ±0   0 ❌ ±0 

Results for commit 1559ad0. ± Comparison against base commit 80bfc9a.