[doc] Update README

[vkarak]

I updated the README in regards with the requirements for running the unit tests.

[codecov-commenter]

Codecov Report

Merging #2294 (d9369d9) into master (3857bad) will not change coverage.
The diff coverage is n/a.

❗ Current head d9369d9 differs from pull request most recent head 27a01ca. Consider uploading reports for the commit 27a01ca to get more accurate results

@@           Coverage Diff           @@
##           master    #2294   +/-   ##
=======================================
  Coverage   86.12%   86.12%           
=======================================
  Files          56       56           
  Lines       10208    10208           
=======================================
  Hits         8792     8792           
  Misses       1416     1416           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 3857bad...27a01ca. Read the comment docs.