Clarify how to get data from Line3D and fix formatting issue

Author: oscargus

lib/mpl_toolkits/mplot3d/art3d.py

@@ -183,6 +183,12 @@ def text_2d_to_3d(obj, z=0, zdir='z'):
 class Line3D(lines.Line2D):
     """
     3D line object.
+
+    .. note:: Use `get_data_3d` to obtain the data associated with the line.
+            `~.Line2D.get_data`, `~.Line2D.get_xdata`, and `~.Line2D.get_ydata` return
+            the x- and y-coordinates of the projected 2D-line, not the x- and y-data of
+            the 3D-line. Similarly, use `set_data_3d` to set the data, not
+            `~.Line2D.set_data`, `~.Line2D.set_xdata`, and `~.Line2D.set_ydata`.
     """
 
     def __init__(self, xs, ys, zs, *args, **kwargs):
@@ -196,8 +202,8 @@ def __init__(self, xs, ys, zs, *args, **kwargs):
             The y-data to be plotted.
         zs : array-like
             The z-data to be plotted.
-
-        Additional arguments are passed onto :func:`~matplotlib.lines.Line2D`.
+        *args, **kwargs :
+            Additional arguments are passed to `~matplotlib.lines.Line2D`.
         """
         super().__init__([], [], *args, **kwargs)
         self.set_data_3d(xs, ys, zs)