Fix typo in progress.md

[ruyut]

Just simple typo fix.

two way -> two ways

Motivation and Context

How Has This Been Tested?

Breaking Changes

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)
• 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

Additional context

[Copilot]

Pull request overview

This pull request fixes a grammatical error in the progress documentation, correcting "two way" to "two ways" when describing how clients can register notification handlers for progress updates.

Changes:

• Fixed grammatical error in progress.md documentation

[stephentoub]

Thanks. We can merge this one, but please batch any future such typo fixes (this is the second PR today with a one word doc change).