Update README.md

[Spartan-119]

Description

Changed "Currently supports Linux and macOS (Windows support coming soon)" to "Compatible with all three types of Operating Systems - Linux, macOS, and Windows".

Affected Dependencies

None

How has this been tested?

Yes.

Checklist

• [x] I have followed the Contribution Guidelines and Code of Conduct
• [x] I have commented my code following the OpenMined Styleguide
• [x] I have labeled this PR with the relevant Type labels
• [x] My changes are covered by tests