Fix example for what's new imshow so it isn't crowded or cut off.

Author: stefmolin

doc/users/next_whats_new/imshow_extent_units.rst

@@ -11,7 +11,7 @@ can now be expressed with units.
     from matplotlib.dates import HourLocator, DateFormatter
     from matplotlib.ticker import AutoMinorLocator
 
-    fig, ax = plt.subplots()
+    fig, ax = plt.subplots(figsize=(6, 6))
     date_first = np.datetime64('2020-01-01', 'D')
     date_last = np.datetime64('2020-01-11', 'D')
 
@@ -20,7 +20,9 @@ can now be expressed with units.
     ax.imshow(arr, origin='lower', extent=[1, 11, date_first, date_last])
 
     ax.yaxis.set_major_formatter(DateFormatter('%d/%m/%y:- %H00hours'))
-    ax.yaxis.set_major_locator(HourLocator(byhour=[0, 6, 12, 18, 24]))
+    ax.yaxis.set_major_locator(HourLocator(byhour=[0, 12, 24]))
     ax.yaxis.set_minor_locator(AutoMinorLocator())
 
+    fig.tight_layout()
+
     plt.show()