Issue #2962765 by juampynr, shubham.prakash: Clarify how to set MINK variables at phpunit.xml.dist

core/phpunit.xml.dist

@@ -24,9 +24,13 @@
     <!-- To disable deprecation testing completely uncomment the next line. -->
     <!-- <env name="SYMFONY_DEPRECATIONS_HELPER" value="disabled"/> -->
     <!-- Example for changing the driver class for mink tests MINK_DRIVER_CLASS value: 'Drupal\FunctionalJavascriptTests\DrupalSelenium2Driver' -->
+    <env name="MINK_DRIVER_CLASS" value=''/>
     <!-- Example for changing the driver args to mink tests MINK_DRIVER_ARGS value: '["http://127.0.0.1:8510"]' -->
+    <env name="MINK_DRIVER_ARGS" value=''/>
     <!-- Example for changing the driver args to phantomjs tests MINK_DRIVER_ARGS_PHANTOMJS value: '["http://127.0.0.1:8510"]' -->
-    <!-- Example for changing the driver args to webdriver tests MINK_DRIVER_ARGS_WEBDRIVER value: '["firefox", null, "http://localhost:4444/wd/hub"]' -->
+    <env name="MINK_DRIVER_ARGS_PHANTOMJS" value=''/>
+    <!-- Example for changing the driver args to webdriver tests MINK_DRIVER_ARGS_WEBDRIVER value: '["firefox", null, "http://localhost:4444/wd/hub"]' For using the Chrome browser, replace "firefox" with "chrome" -->
+    <env name="MINK_DRIVER_ARGS_WEBDRIVER" value=''/>
   </php>
   <testsuites>
     <testsuite name="unit">