docs(tutorial/2 - Angular Templates): Running unit test without Firef…

docs/content/tutorial/step_02.ngdoc

@@ -195,8 +195,30 @@ to ensure that Karma and its necessary plugins are installed. You can do this by
 
 To run the tests, and then watch the files for changes: `npm test`.
 
-* Karma will start a new instance of Chrome browser automatically. Just ignore it and let it run in
-   the background. Karma will use this browser for test execution.
+* Karma will start new instances of Chrome and Firefox browsers automatically. Just ignore them and let them run in
+   the background. Karma will use these browsers for test execution.
+* If you only have one browser installed on your machine (either Chrome or Firefox browser), make sure to update the 
+   karma configuration file before running the test. Locate the configuration file in `test/karma.conf.js`, then
+   update the property of `browsers` to suit with the one you have in your machine.
+
+  If you only have Chrome browser installed: 
+  <pre>
+    ...
+    frameworks: ['jasmine'],
+
+    browsers: ['Chrome'],
+    ...
+  </pre>
+
+  Or if you only have Firefox browser installed:
+  <pre>
+    ...
+    frameworks: ['jasmine'],
+
+    browsers: ['Firefox'],
+    ...
+  </pre>
+
 * You should see the following or similar output in the terminal:
 
   <pre>