add missing auto_examples dirs in clean

Author: pdebuyl

Makefile

@@ -31,7 +31,7 @@ help:
 
 clean:
 	-rm -rf build/*
-	-rm -rf intro/scipy/auto_examples/ intro/matplotlib/auto_examples/ intro/summary-exercises/auto_examples advanced/mathematical_optimization/auto_examples/ advanced/advanced_numpy/auto_examples/ advanced/image_processing/auto_examples advanced/scipy_sparse/auto_examples packages/3d_plotting/auto_examples packages/statistics/auto_examples/ packages/scikit-image/auto_examples/ packages/scikit-learn/auto_examples
+	-rm -rf intro/scipy/auto_examples/ intro/matplotlib/auto_examples/ intro/summary-exercises/auto_examples advanced/mathematical_optimization/auto_examples/ advanced/advanced_numpy/auto_examples/ advanced/image_processing/auto_examples advanced/scipy_sparse/auto_examples packages/3d_plotting/auto_examples packages/statistics/auto_examples/ packages/scikit-image/auto_examples/ packages/scikit-learn/auto_examples intro/numpy/auto_examples guide/auto_examples
 
 test:
 	MATPLOTLIBRC=build_tools $(PYTHON) -m pytest --doctest-glob '*.rst' --ignore advanced/advanced_numpy/examples/myobject_test.py --ignore advanced/interfacing_with_c/numpy_c_api/test_cos_module_np.py --ignore advanced/interfacing_with_c/ctypes/cos_module.py --ignore advanced/interfacing_with_c/swig_numpy/test_cos_doubles.py --ignore advanced/interfacing_with_c/cython_numpy/test_cos_doubles.py --ignore advanced/interfacing_with_c/ctypes_numpy/cos_doubles.py --ignore advanced/interfacing_with_c/ctypes_numpy/test_cos_doubles.py --ignore advanced/interfacing_with_c/numpy_shared/test_cos_doubles.py