docs/devel/testing.rst: add missing newlines after code block

The line immediate following a ".. code::" block is considered
to contains arguments to the "code directive".  The lack of a
new line gives me during at parse time:

   testing.rst:63: (ERROR/3) Error in "code" directive:
   maximum 1 argument(s) allowed, 3 supplied.

   .. code::
     make check-unit V=1

   testing.rst:120: (ERROR/3) Error in "code" directive:
   maximum 1 argument(s) allowed, 3 supplied.

   .. code::
     make check-qtest V=1

Let's add the missing newlines, both for consistency and to
avoid the parsing errors.
Signed-off-by: NCleber Rosa <crosa@redhat.com>
Reviewed-by: NJohn Snow <jsnow@redhat.com>
Message-Id: <20181004161852.11673-6-crosa@redhat.com>
Signed-off-by: NLaurent Vivier <laurent@vivier.eu>

docs/devel/testing.rst

@@ -59,6 +59,7 @@ variable (which affects memory reclamation and catches invalid pointers better)
 and gtester options. If necessary, you can run
 
 .. code::
+
   make check-unit V=1
 
 and copy the actual command line which executes the unit test, then run
@@ -116,6 +117,7 @@ and using gdb on the test is still simple to do: find out the actual command
 from the output of
 
 .. code::
+
   make check-qtest V=1
 
 which you can run manually.