docs/source/GetStartedGuide.rst: some changes to wording that add more consistency

It's obviously not true that Avocado only allows to run tests on "your laptop".
Also let's keep the running of tests and the outcome all in the present tense.
Signed-off-by: NCleber Rosa <crosa@redhat.com>

docs/source/GetStartedGuide.rst

@@ -59,14 +59,13 @@ For Debian users, use `apt-get` to install the proper dependencies that `yum` in
 Using the avocado test runner
 =============================
 
-The test runner is designed to conveniently run tests on your laptop. The tests
-you can run are:
+The test runner is designed to conveniently run tests on your local machine. The types of
+tests you can run are:
 
-* Tests written in python, using the avocado API, which we'll call
-  `instrumented`.
+* Tests written in Python, using the avocado API, which we'll call `instrumented`.
 * Any executable in your box, really. The criteria for PASS/FAIL is the return
-  code of the executable. If it returns 0, the test PASSed, if it returned
-  != 0, it FAILed. We'll call those tests `simple tests`. There is another type
+  code of the executable. If it returns 0, the test PASSes, if it returns anything
+  else, it FAILs. We'll call those tests `simple tests`. There is another type
   of tests that we'll discuss in the next section.
 
 Listing tests