Fix markup in unittest docs.

Doc/library/unittest.rst

@@ -1868,10 +1868,10 @@ name then the package :file:`__init__.py` will be checked for ``load_tests``.
 
 .. note::
 
-   The default pattern is 'test*.py'. This matches all Python files
-   that start with 'test' but *won't* match any test directories.
+   The default pattern is ``'test*.py'``. This matches all Python files
+   that start with ``'test'`` but *won't* match any test directories.
 
-   A pattern like 'test*' will match test packages as well as
+   A pattern like ``'test*'`` will match test packages as well as
    modules.
 
 If the package :file:`__init__.py` defines ``load_tests`` then it will be