Update README.md

[tjoyal]

I am still in the process of exploring the gem, and here are the initial challenges I've encountered that have slowed my progress.

• Remove the example controller from the gem module (avoid implicit relationship)
• server.handle_json seems to always return a String, I am still reading through the code, I'm I missing something? Is this expected?
• server.handle_json have been returning nil when passed a notifications/initialized.
• Add missing module in tool example

Motivation and Context

Hopefully it helps someone. From 0 to 1 is there hard part in adopting a new gem.

How Has This Been Tested?

Playing around locally

Breaking Changes

Documentation only

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [x] Documentation update

Checklist

• [ ] I have read the MCP Documentation
• [ ] My code follows the repository's style guidelines
• [ ] New and existing tests pass locally
• [ ] I have added appropriate error handling
• [ ] I have added or updated documentation as needed