revert the wrongly changed test code

src/zope/testrunner/tests/testrunner-discovery.txt

@@ -46,26 +46,3 @@ testrunner will exit with an error to prevent acidentally missing test cases:
       sample1.sampletests_discover_notests
     Total: 0 tests, 0 failures, 0 errors and 0 skipped in 0.000 seconds.
     True
-
-You can explicitly specify which tests to run by providing a function that
-returns a unittest.TestSuite in the test modules (the name of the function can
-be configured with the --suite-name parameter, it defaults to 'test_suite'). If
-no such function is present, testrunner will use all classes in the module that
-inherit from unittest.TestCase as tests:
-
-    >>> import os, sys
-    >>> directory_with_tests = os.path.join(this_directory, 'testrunner-ex')
-
-    >>> from zope import testrunner
-
-    >>> defaults = [
-    ...     ]
-    >>> sys.argv = ['test',
-    ...     ]
-    >>> testrunner.run(defaults)
-    Running zope.testrunner.layer.UnitTests tests:
-      Set up zope.testrunner.layer.UnitTests in N.NNN seconds.
-      Ran 2 tests with 0 failures, 0 errors and 0 skipped in N.NNN seconds.
-    Tearing down left over layers:
-      Tear down zope.testrunner.layer.UnitTests in N.NNN seconds.
-    False