Merge pull request matplotlib#23600 from scottshambaugh/3d_primary_views_docs

DOC: view_init docstring for 3d axes primary view angles

Author: timhoffm

lib/mpl_toolkits/mplot3d/axes3d.py

@@ -738,6 +738,21 @@ def view_init(self, elev=None, azim=None, roll=None, vertical_axis="z"):
 
         This can be used to rotate the axes programmatically.
 
+        To look normal to the primary planes, the following elevation and
+        azimuth angles can be used. A roll angle of 0, 90, 180, or 270 deg
+        will rotate these views while keeping the axes at right angles.
+
+        ==========   ====  ====
+        view plane   elev  azim
+        ==========   ====  ====
+        XY           90    -90
+        XZ           0     -90
+        YZ           0     0
+        -XY          -90   90
+        -XZ          0     90
+        -YZ          0     180
+        ==========   ====  ====
+
         Parameters
         ----------
         elev : float, default: None