DOC: Added plt.show() at the end of each necessary block (pandas-dev#45772)

Reworded and moved title to the top of the page

Author: ehallam

doc/source/getting_started/intro_tutorials/04_plotting.rst

@@ -188,7 +188,7 @@ Some more formatting options are explained in the user guide section on :ref:`pl
 I want to further customize, extend or save the resulting plot.
 
 .. ipython::
-    @04_airqual_customized.png
+    @savefig 04_airqual_customized.png
     In [1]: fig, axs = plt.subplots(figsize=(12, 4))
        ...: air_quality.plot.area(ax=axs)
        ...: axs.set_ylabel("NO$_2$ concentration")