Add example command line for running unit tests (was not obvious to me how to run tests).

README.md

@@ -40,6 +40,8 @@ required for proper controller tests.
 
 4. Run the unit tests first time for installing test database. It will take about 3 minutes.
 
+        $ phpunit UnitTests.php
+
 5. If it shows that there was no tests found, it means that extension was successfully
 installed. If it shows some errors than it means that your customizations has install
 scripts that relay on your current database data so you should fix them.
@@ -58,6 +60,8 @@ required for proper controller tests.
 
 3. Run the unit tests first time for installing test database. It will take about 3 minutes.
 
+        $ phpunit UnitTests.php
+
 4. If it shows that there was no tests found, it means that extension was successfully
 installed. If it shows some errors than it means that your customizations has install
 scripts that relay on your current database data so you should fix them.