Fix 1223 - Updated Readme file

[Barathwaja]

Fixed Issues #1223 with updating the instruction for setting ENV Variable.

Checklist

• I have read the contribution guidelines.
• I added or modified the existing tests to cover the change (we do not allow our test coverage to go down).
• If this is a modification that impacts the behavior of a public API
  • I edited the corresponding document in the devdoc folder and added or modified requirements.

Reference/Link to the issue solved with this PR (if any)

PR #1223