DOC: Add [*Discouraged*] prefix to summary lines

Apply matplotlib#29303 where it was missing

Author: timhoffm

lib/matplotlib/axes/_base.py

@@ -3602,7 +3602,7 @@ def set_xlabel(self, xlabel, fontdict=None, labelpad=None, *,
 
     def invert_xaxis(self):
         """
-        Invert the x-axis.
+        [*Discouraged*] Invert the x-axis.
 
         .. admonition:: Discouraged
 
@@ -3870,7 +3870,7 @@ def set_ylabel(self, ylabel, fontdict=None, labelpad=None, *,
 
     def invert_yaxis(self):
         """
-        Invert the y-axis.
+        [*Discouraged*]  Invert the y-axis.
 
         .. admonition:: Discouraged
 

lib/matplotlib/axis.py

@@ -1443,7 +1443,7 @@ def set_label(self, s):
 
     def get_label(self):
         """
-        Return the axis label as a Text instance.
+        [*Discouraged*] Return the axis label as a Text instance.
 
         .. admonition:: Discouraged
 

lib/mpl_toolkits/mplot3d/axes3d.py

@@ -1886,7 +1886,7 @@ def tick_params(self, axis='both', **kwargs):
 
     def invert_zaxis(self):
         """
-        Invert the z-axis.
+        [*Discouraged*] Invert the z-axis.
 
         .. admonition:: Discouraged