Fix in README.md to use right request_context syntax

[AishwaryaKalloli]

Fix in README.md to use right request_context syntax as discussed in discussion in the issue.
TESTED = all current tests pass

Motivation and Context

Addressing the issue in documentations as discussed here.

How Has This Been Tested?

TESTED = all current tests pass

Breaking Changes

No

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

[Kludex]

• I went with [DOC] Fix example usage of get_context (plus a little more) #801

Thanks for the PR. :)