Update README.md RN50 on BH

[mbahnasTT]

Ticket

Link to Github Issue

Problem description

Provide context for the problem.

What's changed

Describe the approach used to solve the problem.
Summarize the changes made and its impact.

Checklist

• All post commit CI passes
• Blackhole Post commit CI passes (if applicable)
• Model regression CI passes (if applicable)
• Device performance regression CI passes (if applicable)
• (For models and ops writers) Full new models tests CI passes (if applicable)
• New/Existing tests provide coverage for changes