docs(NODE-6339): update README testing section (#199)

Author: aditi-khare-mongoDB

README.md

@@ -93,10 +93,10 @@ To verify the native `.node` packages, follow the same steps as above.
 Run the test suite using:
 
 ```bash
-npm test
+docker run -i -v PATH_TO_KERBEROS_REPO:/app -w /app -e PROJECT_DIRECTORY=/app ubuntu:20.04 /bin/bash /app/.evergreen/run-tests-ubuntu.sh
 ```
 
-NOTE: The test suite requires an active kerberos deployment, see `test/scripts/travis.sh` to better understand these requirements.
+NOTE: The test suite requires an active kerberos deployment.
 
 # Documentation