Small doc fixes

Author: dstansby

doc/users/next_whats_new/2017-12-08-axline.rst

@@ -1,5 +1,5 @@
 New `axline` method
 -------------------
 
-A new `axline` method has been added to draw infinitely long lines that pass
-through two points.
+A new `~.axes.Axes.axline` method has been added to draw infinitely long lines
+that pass through two points.

lib/matplotlib/axes/_axes.py

@@ -816,6 +816,7 @@ def axhline(self, y=0, xmin=0, xmax=1, **kwargs):
         --------
         hlines : Add horizontal lines in data coordinates.
         axhspan : Add a horizontal span (rectangle) across the axis.
+        axhline : Add a line with an arbitrary slope.
 
         Examples
         --------
@@ -899,6 +900,7 @@ def axvline(self, x=0, ymin=0, ymax=1, **kwargs):
         --------
         vlines : Add vertical lines in data coordinates.
         axvspan : Add a vertical span (rectangle) across the axis.
+        axline : Add a line with an abritrary slope.
         """
 
         if "transform" in kwargs:
@@ -942,7 +944,7 @@ def axline(self, xy1, xy2, **kwargs):
 
         Examples
         --------
-        * Draw a thick red line passing through (0, 0) with a gradient of 1::
+        Draw a thick red line passing through (0, 0) and (1, 1)::
 
             >>> axline((0, 0), (1, 1), linewidth=4, color='r')