Update README link in PYTEST_FUNCTION comment to point to the correct documentation (apache#62197)

Author: aaron-y-chen

scripts/ci/prek/check_system_tests.py

@@ -46,7 +46,7 @@
 PYTEST_FUNCTION = """
 from tests_common.test_utils.system_tests import get_test_run  # noqa: E402
 
-# Needed to run the example DAG with pytest (see: tests/system/README.md#run_via_pytest)
+# Needed to run the example DAG with pytest (see: contributing-docs/testing/system_tests.rst)
 test_run = get_test_run(dag)
 """
 PYTEST_FUNCTION_PATTERN = re.compile(