Clarify run tests step in contributing guidelines.

Author: nlutsenko

CONTRIBUTING.md

@@ -7,7 +7,7 @@ We really want Parse to be yours, to see it grow and thrive in the open source c
 ##### Please Do's
 
 * Take testing seriously! Aim to increase the test coverage with every pull request.
-* Run the tests for the file you are working on with `TESTING=1 (repo-root)/node_modules/jasmine/bin/jasmine.js spec/MyFile.spec.js`
+* Run the tests for the file you are working on with `npm test spec/MyFile.spec.js`
 * Run the tests for the whole project and look at the coverage report to make sure your tests are exhaustive by running `npm test` and looking at (project-root)/lcov-report/parse-server/FileUnderTest.js.html
 
 ##### Code of Conduct