Fix code blocks

Author: nikic

Book/tests/running_the_test_suite.rst

@@ -90,17 +90,19 @@ You can specify multiple target folders or files to run by separating each path
 Executing tests in parallel
 ---------------------------
 
-Since PHP 7.4 you are able to run tests in parallel by passing a ``-j<workers>`` flag, where workers is the number of parallel processes you want. e.g. ``-j4`` would run 4 tests at once.
+Since PHP 7.4 you are able to run tests in parallel by passing a ``-j<workers>`` flag to ``run-tests.php``, where ``<workers>`` is the number of parallel processes you want. For example, ``-j4`` would run 4 tests at once.
 
 Example for running tests through run-tests.php:
-```
-run-tests.php -j8
-```
+
+.. code-block:: bash
+
+    run-tests.php -j8
 
 Example for running tests through make:
-```
-make test TESTS="-j8"
-```
+
+.. code-block:: bash
+
+    make test TESTS="-j8"
 
 More options
 ------------