DOC: lineplot/xlims whatsnew entry for v0.21.0

Author: nmartensen

doc/source/whatsnew/v0.21.0.txt

@@ -522,6 +522,8 @@ Plotting
 ^^^^^^^^
 - Bug in plotting methods using ``secondary_y`` and ``fontsize`` not setting secondary axis font size (:issue:`12565`)
 - Bug when plotting ``timedelta`` and ``datetime`` dtypes on y-axis (:issue:`16953`)
+- Line plots no longer assume monotonic x data when calculating xlims, they show the entire lines now even for unsorted x data. (:issue:`11310`)(:issue:`11471`)
+- With matplotlib 2.0.0 and above, calculation of x limits for line plots is left to matplotlib, so that its new default settings are applied. (:issue:`15495`)
 
 Groupby/Resample/Rolling
 ^^^^^^^^^^^^^^^^^^^^^^^^