Update README with disclaimer

[khareRajshree]

Description
This PR adds the disclaimer to the README file.

GitHub Issues

List the GitHub issues impacted by this PR:

GitHub Issue #
https://github.com/dell/csm/issues/1896

Checklist:

• I have performed a self-review of my own code to ensure there are no formatting, vetting, linting, or security issues
• I have verified that new and existing unit tests pass locally with my changes
• I have not allowed coverage numbers to degenerate
• I have maintained at least 90% code coverage
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• Backward compatibility is not broken

How Has This Been Tested?

The disclaimer content has been reviewed and validated by all required stakeholders.